Re: Frank King

[Richard Langley]

I run into that problem all the time concerning GPS and GNSS. Even editors of 
technical magazines are often not fully scientifically literate. In the 
editorial of a GNSS magazine this month, the editor stated that an asterism was 
a group of constellations! :-(

-- Richard Langley

-
| Richard B. LangleyE-mail: l...@unb.ca |
| Geodetic Research Laboratory  Web: http://gge.unb.ca/ |
| Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142   |
| University of New Brunswick   Fax:  +1 506 453-4943   |
| Fredericton, N.B., Canada  E3B 5A3|
|Fredericton?  Where's that?  See: http://www.fredericton.ca/   |
-



> On Feb 21, 2019, at 8:57 AM, Frank King  wrote:
> 
> Dear Willy et al,
> 
> You are quite right...
> 
>> There are two fundamental errors in the
>> article by David Leafe for the Daily Mail.
> 
> He spent an hour on the telephone to me
> yesterday evening.  He went through his
> text about 20 times.  The big problem, for
> me, was trying to explain the difference
> between latitude and longitude!
> 
> An even bigger problem was that his Editor
> kept reminding himthat the text must be
> something that Daily Mail readers could
> understand!
> 
> I thought he had got everything right but
> his Editor must have back-tracked a couple
> of versions.  No doubt Daily Mail readers
> will be happy :-)
> 
> Moral: never believe what you read in the
> newspapers even when it is quoting me.
> 
> Very best wishes
> 
> Frank
> 
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
> 

---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: How good is a cell phone compass

[Richard Langley]

And if you were still at UNB, we could have used a theodolite to line things up 
similar to what I had to do (or, rather, have a student do) when helping to 
refurbish the Fredericton Soldiers Barracks wall sundial a number of years ago. 
;-)
-- Richard

-
| Richard B. LangleyE-mail: l...@unb.ca |
| Geodetic Research Laboratory  Web: http://gge.unb.ca  |
| Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142   |
| University of New Brunswick   Fax:  +1 506 453-4943   |
| Fredericton, N.B., Canada  E3B 5A3|
|Fredericton?  Where's that?  See: http://www.fredericton.ca/   |
-


From: sundial  on behalf of Richard Langley 

Sent: September 11, 2018 4:49 PM
To: Steve Lelievre; Sundial List
Subject: Re: How good is a cell phone compass

Hi Steve:
My iPhone compass app is indicating N correctly to within 1° right now with the 
phone sitting on the dining room table in a wood-frame house. Calibration not 
performed recently. Fortuitous? There must be some specs somewhere on the Web.
-- Richard

-
| Richard B. LangleyE-mail: l...@unb.ca |
| Geodetic Research Laboratory  Web: http://gge.unb.ca  |
| Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142   |
| University of New Brunswick   Fax:  +1 506 453-4943   |
| Fredericton, N.B., Canada  E3B 5A3|
|Fredericton?  Where's that?  See: http://www.fredericton.ca/   |
-


From: sundial  on behalf of Steve Lelievre 

Sent: September 11, 2018 4:38 PM
To: Sundial List
Subject: How good is a cell phone compass

Hi everyone,

How good is a cell phone compass? I mean, if I have no metal nearby and
I have the phone set to show True North, what kind of accuracy can I
expect if I lay my phone flat and use the compass app?

I'm working on a vertical west sundial for a community garden (a.k.a
allotment) and have a deadline of end of September to get it installed,
because the aim is to unveil it at the group's annual meeting.

The dial is to be installed on two posts. I want to get the posts lined
up as close to north-south as I can, to make aligning the dial easier. I
will use adjustable bolts to fix the dial to the posts, so can I
compensate for the line between them being a couple of degrees off - but
no more than that.

I already have one post installed and concreted in place. I had hoped to
use the sun's meridian shadow cast by it to give me a precise line N-S
for placing the second post. Unfortunately, rain has set in here and it
looks as if there will not be a sunny day for at least a week. I don't
think I can wait that long to get the second post installed; otherwise
I'll be short of time for the other remaining tasks. Hence my interest
in using my phone compass for alignment.

Cheers,

Steve






---
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---
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Re: How good is a cell phone compass

[Richard Langley]

Hi Steve:
My iPhone compass app is indicating N correctly to within 1° right now with the 
phone sitting on the dining room table in a wood-frame house. Calibration not 
performed recently. Fortuitous? There must be some specs somewhere on the Web.
-- Richard  

-
| Richard B. LangleyE-mail: l...@unb.ca |
| Geodetic Research Laboratory  Web: http://gge.unb.ca  |
| Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142   |
| University of New Brunswick   Fax:  +1 506 453-4943   |
| Fredericton, N.B., Canada  E3B 5A3|
|Fredericton?  Where's that?  See: http://www.fredericton.ca/   |
-


From: sundial  on behalf of Steve Lelievre 

Sent: September 11, 2018 4:38 PM
To: Sundial List
Subject: How good is a cell phone compass

Hi everyone,

How good is a cell phone compass? I mean, if I have no metal nearby and
I have the phone set to show True North, what kind of accuracy can I
expect if I lay my phone flat and use the compass app?

I'm working on a vertical west sundial for a community garden (a.k.a
allotment) and have a deadline of end of September to get it installed,
because the aim is to unveil it at the group's annual meeting.

The dial is to be installed on two posts. I want to get the posts lined
up as close to north-south as I can, to make aligning the dial easier. I
will use adjustable bolts to fix the dial to the posts, so can I
compensate for the line between them being a couple of degrees off - but
no more than that.

I already have one post installed and concreted in place. I had hoped to
use the sun's meridian shadow cast by it to give me a precise line N-S
for placing the second post. Unfortunately, rain has set in here and it
looks as if there will not be a sunny day for at least a week. I don't
think I can wait that long to get the second post installed; otherwise
I'll be short of time for the other remaining tasks. Hence my interest
in using my phone compass for alignment.

Cheers,

Steve






---
https://lists.uni-koeln.de/mailman/listinfo/sundial

---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: The Palace Sundial

[Richard Langley]

Buckingham Palace, I presume. Mere mortals ordinarily can't get in there. ;-)
-- Richard Langley

Sent from my iPhone

On Apr 10, 2018, at 9:25 PM, Roger Bailey 
<rtbai...@telus.net<mailto:rtbai...@telus.net>> wrote:

Which palace? I found two sundials at Windsor Castle, both in the sun. One is a 
vertical declining  sundial dated 1723 is carved on the south face of the Lady 
Chapel of St Georges Chapel. The other is an armillary in a garden below ther 
the Round Tower. They are waymarked here.
http://www.waymarking.com/waymarks/WMF2Y3_St_Georges_Chapel_Sundial_Windsor_Castle_UK
http://www.waymarking.com/waymarks/WMF2Y6_Armillary_Sundial_Windsor_Castle_UK

Regards,
Roger Bailey
aka arby101ca


--
From: "Richard B. Langley" <l...@unb.ca<mailto:l...@unb.ca>>
Sent: Tuesday, April 10, 2018 11:19 AM
To: "sundial list" <sundial@uni-koeln.de<mailto:sundial@uni-koeln.de>>
Subject: The Palace Sundial

> The Queen and Sir David Attenborough saw the funny side when they came across 
> a strangely placed sundial in the palace grounds:
> http://www.bbc.com/news/av/uk-43714489/her-majesty-and-the-naturalist-took-a-stroll-around-the-palace-grounds
>
> -- Richard Langley
>
> -
> | Richard B. LangleyE-mail: 
> l...@unb.ca<mailto:l...@unb.ca> |
> | Geodetic Research Laboratory  Web: http://gge.unb.ca/ |
> | Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142   |
> | University of New Brunswick   Fax:  +1 506 453-4943   |
> | Fredericton, N.B., Canada  E3B 5A3|
> |Fredericton?  Where's that?  See: http://www.fredericton.ca/   |
> -
>
>
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>



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This email has been checked for viruses by Avast antivirus software.
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Re: publication on Science of Time, with sundials

[Richard Langley]

Whoops! Fake news! Einstein did get a Nobel prize but not for relativity. He 
got it in 1921 for explaining the photoelectric effect.
-- Richard Langley

Sent from my iPhone

On Nov 4, 2017, at 4:08 PM, Brooke Clarke 
<bro...@pacific.net<mailto:bro...@pacific.net>> wrote:

Hi Rod:

Using time sent over telegraph wires allowed determining longitude much more 
accurately than was possible before because time could be transferred more 
accurately than prior.  But this also created a problem in setting clocks.  In  
the late 1800s and early 1900s there were a lot of patent applications on ways 
to do this and a guy named Einstein who worked in the Swiss patent office read 
pretty much all of them in his office.  People were beginning to see what today 
we would call relativistic differences but at that time they just saw problems. 
 Note that Eisenstein never received a Nobel prize because he was just a patent 
clerk, not a scientist.

A common misconception is that Newton was a physicist who figured out what 
gravity is.  Not at all true.  Newton was a mathematician who invented 
mathematics to make "black box" calculations about gravity but had no clue how 
it worked.  More about this in the Richard Feynman lectures at Cornell 
"The.Character of Physical Law".
https://www.microsoft.com/en-us/research/project/tuva-richard-feynman/
also the book: Einstein's Clocks and Poincare's Maps: Empires of Time

--
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html


 Original Message 
Thanks Sara,

A very interesting book. Haven't finished reading it but will.

It reminds me of a book that I once read about time.

Book indicated that when the telegraph lines were invented. This then allowed 
time to be accurate at the end of the telegraph line. Which then allowed the 
location longitude to be accurately defined. And more places as the telegraph 
lines were extended. And even more places when wireless was invented.

Time is very interesting.

 John Harrison's Longitude watch also allowed the longitude to be determined 
more accurately at sea. The story of Longitude and time.

Regards,

Roderick Wall.
At the end of the line in Australia.

- Reply message -
From: "Schechner, Sara" 
<sche...@fas.harvard.edu><mailto:sche...@fas.harvard.edu>
To: "Richard Langley" <l...@unb.ca><mailto:l...@unb.ca>
Cc: "sundial@uni-koeln.de"<mailto:sundial@uni-koeln.de> 
<sundial@uni-koeln.de><mailto:sundial@uni-koeln.de>
Subject: publication on Science of Time, with sundials
Date: Fri, Nov 3, 2017 6:50 AM


Dear All,
The links were free to me and others, but perhaps we are somehow inside the 
firewall.  I don't understand what is going on, since I have not logged into 
the Springer site.

Here is a link to my download of the book: 
https://www.dropbox.com/s/uly1qfaov3intr1/Science%20of%20Time%202016%20BOOK_978-3-319-59909-0.pdf?dl=0

I hope this will help.
Sara


-Original Message-
From: Richard Langley [mailto:l...@unb.ca]
Sent: Thursday, November 02, 2017 3:27 PM
To: Schechner, Sara
Cc: sundial@uni-koeln.de<mailto:sundial@uni-koeln.de>
Subject: Re: publication on Science of Time, with sundials

For free? Not when I followed the links.
-- (Prof.) Richard Langley

-
| Richard B. LangleyE-mail: 
l...@unb.ca<mailto:l...@unb.ca> |
| Geodetic Research Laboratory  Web: http://gge.unb.ca/ |
| Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142   |
| University of New Brunswick   Fax:  +1 506 453-4943   |
| Fredericton, N.B., Canada  E3B 5A3|
|Fredericton?  Where's that?  See: http://www.fredericton.ca/   |
-



> On Nov 2, 2017, at 3:43 PM, Schechner, Sara 
> <sche...@fas.harvard.edu><mailto:sche...@fas.harvard.edu> wrote:
>
> Dear Friends,
>
> In June 2016, I attended a symposium on the Science of Time.  The
> proceedings have now been published by Springer, and are available for
> free download here:
> https://link.springer.com/book/10.1007/978-3-319-59909-0
>
> The Science of Time 2016: Time in Astronomy & Society, Past, Present
> and Future Edited by  Elisa Felicitas Arias, Ludwig Combrinck, Pavel Gabor, 
> Catherine Hohenkerk, and P. Kenneth Seidelmann.
> Astrophysics and Space Science Proceedings, vol 50.
> Cham: Springer International Publishing AG, 2017
>
> Many articles may be of interest to this group, but in particular there are 
> two articles on sundials.  I list them below along with direct links ot the 
> PDFs:
>
> Geoff Parsons:  "The Development and Use of th

Re: publication on Science of Time, with sundials

[Richard Langley]

For free? Not when I followed the links.
-- (Prof.) Richard Langley

-
| Richard B. LangleyE-mail: l...@unb.ca |
| Geodetic Research Laboratory  Web: http://gge.unb.ca/ |
| Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142   |
| University of New Brunswick   Fax:  +1 506 453-4943   |
| Fredericton, N.B., Canada  E3B 5A3|
|Fredericton?  Where's that?  See: http://www.fredericton.ca/   |
-



> On Nov 2, 2017, at 3:43 PM, Schechner, Sara <sche...@fas.harvard.edu> wrote:
> 
> Dear Friends,
>  
> In June 2016, I attended a symposium on the Science of Time.  The proceedings 
> have now been published by Springer, and are available for free download 
> here:  https://link.springer.com/book/10.1007/978-3-319-59909-0
>  
> The Science of Time 2016: Time in Astronomy & Society, Past, Present and 
> Future
> Edited by  Elisa Felicitas Arias, Ludwig Combrinck, Pavel Gabor, Catherine 
> Hohenkerk, and P. Kenneth Seidelmann.
> Astrophysics and Space Science Proceedings, vol 50.
> Cham: Springer International Publishing AG, 2017
>  
> Many articles may be of interest to this group, but in particular there are 
> two articles on sundials.  I list them below along with direct links ot the 
> PDFs:
>  
> Geoff Parsons:  “The Development and Use of the Pilkington and Gibbs 
> Heliochronometer and Sol Horometer”
> https://link.springer.com/content/pdf/10.1007%2F978-3-319-59909-0_7.pdf
>  
> Sara J. Schechner:  “These Are Not Your Mother’s Sundials: Or, Time and 
> Astronomy’s Authority”
> https://link.springer.com/content/pdf/10.1007%2F978-3-319-59909-0_8.pdf
>  
> Happy reading!
> Sara
>  
> Sara J. Schechner, Ph.D.
> David P. Wheatland Curator of the Collection of Historical Scientific 
> Instruments
> Lecturer on the History of Science
> Department of the History of Science, Harvard University
> Science Center 251c, 1 Oxford Street, Cambridge, MA 02138
> Tel: 617-496-9542   |   Fax: 617-495-3344  |   sche...@fas.harvard.edu  
> |@SaraSchechner
> http://scholar.harvard.edu/saraschechner
> http://chsi.harvard.edu/
>  
>  
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial

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Re: Solar watchface for a Pebble smartwatch

[Richard Langley]

Nice but be aware:
https://www.theguardian.com/technology/2016/dec/08/kickstarter-pebble-shut-down
-- Richard Langley

-
| Richard B. LangleyE-mail: l...@unb.ca |
| Geodetic Research Laboratory  Web: http://gge.unb.ca/ |
| Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142   |
| University of New Brunswick   Fax:  +1 506 453-4943   |
| Fredericton, N.B., Canada  E3B 5A3|
|Fredericton?  Where's that?  See: http://www.fredericton.ca/   |
-



> On Apr 27, 2017, at 11:10 AM, Dan-George Uza <cerculdest...@gmail.com> wrote:
> 
> Hello,
> 
> I've recently bought a Pebble smartwatch and I thought I'd share my favorite 
> watchface with you. 
> 
> It's called "Solar watch". It displays the current date, outside temperature, 
> standard time (in white), but also sunrise and sunset times, as well as local 
> apparent solar time (in black). The hour hand shows the Sun's daily progress 
> on a 24 h circular dial featuring solar hours. Civil, nautical and 
> astronomical twilight markers are also present. What I like most about the 
> Pebble is its retro/toy-ish look and above average battery life although the 
> screen stays always on and is very easy to read in the sun.
> 
> Greetings,
> 
> Dan Uza
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
> 

---
https://lists.uni-koeln.de/mailman/listinfo/sundial

An Interesting BBC World Service Program on the Clock

[Richard Langley]

I had previously overlooked the episode "Clock" in the series "50 Things That 
Made the Modern Economy." Luckily, it can be listened to again or downloaded as 
a podcast:
http://www.bbc.co.uk/programmes/p04skkw4

-- Richard Langley
  
-
| Richard B. LangleyE-mail: l...@unb.ca |
| Geodetic Research Laboratory  Web: http://gge.unb.ca/ |
| Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142   |
| University of New Brunswick   Fax:  +1 506 453-4943   |
| Fredericton, N.B., Canada  E3B 5A3|
|Fredericton?  Where's that?  See: http://www.fredericton.ca/   |
-



---
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Re: Time question on GPS TIME and leap second.

[Richard Langley]

"This causes problems for GPS receivers that are more than a few years old 
since they have no idea what year it is."


Not quite true. One of the continuously operating receivers at UNB is more than 
15 years old. Please see:

http://gauss2.gge.unb.ca/gpsworld/gpsworld.november98.pdf​


-- Richard Langley


-
| Richard B. LangleyE-mail: l...@unb.ca |
| Geodetic Research Laboratory  Web: 
http://gge.unb.ca<http://gge.unb.ca/>  |
| Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142   |
| University of New Brunswick   Fax:  +1 506 453-4943   |
| Fredericton, N.B., Canada  E3B 5A3|
|Fredericton?  Where's that?  See: 
http://www.fredericton.ca/<https://unbmail.unb.ca/owa/redir.aspx?C=tVxi5OaRXE2jUmSNTu0wE7USusV6L9AIh-TKOqhq1DE--EjKeq-SUal8Myg-FGJn53Gm890SFIc.=http%3a%2f%2fwww.fredericton.ca%2f>
   |
-

From: sundial <sundial-boun...@uni-koeln.de> on behalf of Brooke Clarke 
<bro...@pacific.net>
Sent: Monday, January 30, 2017 4:29 PM
To: sundial list
Subject: Re: Time question on GPS TIME and leap second.

Hi Roderick:

GPS time is continuous, that's to say there are no leap seconds or other 
changes to it since it started.  It uses a 10 bit binary week counter so the 
week number rolls over after 1024 weeks.  This causes problems for GPS 
receivers that are more than a few years old since they have no idea what year 
it is.
The total number of seconds offset from UTC is transmitted separately so that a 
GPS receiver can display either GPS time or UTC.
Note that the time and position are independent from the year.

http://www.prc68.com/I/Trimpack.shtml#WkRlvr

--
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html


 Original Message 
Hi all,

Was just listening to the CrowdScience on time. Thanks to whoever posted the 
link to it.

CrowdScience indicated that a leap second was not added for the GPS. They also 
indicated that the GPS gives us UTC time.

Question:
The UTC time that the GPS gives. Does that have the leap second added?

Thanks,

Regards,

Roderick Wall.

- Reply message -
From: "Michael Ossipoff" <email9648...@gmail.com><mailto:email9648...@gmail.com>
To: "Robert Kellogg" <rkell...@comcast.net><mailto:rkell...@comcast.net>
Cc: "sundial list" <sundial@uni-koeln.de><mailto:sundial@uni-koeln.de>
Subject: Why we should reform the Calendar
Date: Mon, Jan 30, 2017 8:00 AM


On Sun, Jan 29, 2017 at 2:41 PM, Robert Kellogg 
<rkell...@comcast.net><mailto:rkell...@comcast.net>
wrote:

> Michael goes off looking for the ideal tropical year


There isn't an "ideal tropical year", but, as a choice for a
leapyear-rule's mean-year, the length of the mean tropical year (MTY) is
best for year-round reduction of longterm calendar-drift.  ...and the
average of the lengths of the March & September Equinox tropical years
(I'll call that the Average Equinox Year (AEY) ) is a compromise between
the vernal equinoxes of the North & the South.


> , perhaps ignoring effects of the earth's nutations.
>

Of course. The nutations are small in amplitude & period. They aren't part
of calendar rules. The mean equinox (nutations averaged-out) is the one
that is meant when the equinox is spoken of with regard to calendars.



> I'll still take the one of 1900, most importantly because it defines the
> SI second.


The SI second was defined as 1/86,400 of a mean solar day, for some year in
the early 19th century. I don't remember exactly what year that was. 1820?
1840? 1850?

Evidently it isn't practical to update the length of the SI second, but
that doesn't mean that calendars have to be based on the ephemeris day, or
atomic day, consisting of 86,400 SI seconds, when that's known to be
different from today's mean solar day.

That's why I suggest 365.24217 instead of 365.24219 for the length of the
mean tropical year (MTYI. It makes sense to base a calendar leap-year
rule's mean-year on the actual length of a tropical-year (whichever one we
want to use) on the length of that tropical year in* today's* mean days.


>
>
> So, contemplating changing the year is non trivial.


Evidently there must be some reason why it would be impractical to update
the length of the SI second. But it isn't necessary to call a MTY 365.24219
days, when it's really 365.24217 mean days long.   ...for the purposes of a
calendar leapyear rule. There's inevitable inaccuracy due to rounding-off,
and due to gradual change in the lengths of all the tropical years,
including the MTY. But that doesn't mea

Re: Time question on GPS TIME and leap second.

[Richard Langley]

Here is a link to an old GPS World article on GPS and the leap second:

http://www2.unb.ca/gge/Resources/gpsworld.november99.pdf

See the "The GPS Navigation Message" sidebar in particular.

And an article from GPS World on the occasion of the previous leap second:

http://gpsworld.com/its-leap-second-day-time-to-get-in-sync/


-- Richard Langley


-
| Richard B. LangleyE-mail: l...@unb.ca |
| Geodetic Research Laboratory  Web: 
http://gge.unb.ca<http://gge.unb.ca/>  |
| Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142   |
| University of New Brunswick   Fax:  +1 506 453-4943   |
| Fredericton, N.B., Canada  E3B 5A3|
|Fredericton?  Where's that?  See: 
http://www.fredericton.ca/<https://unbmail.unb.ca/owa/redir.aspx?C=tVxi5OaRXE2jUmSNTu0wE7USusV6L9AIh-TKOqhq1DE--EjKeq-SUal8Myg-FGJn53Gm890SFIc.=http%3a%2f%2fwww.fredericton.ca%2f>
   |
-

From: sundial <sundial-boun...@uni-koeln.de> on behalf of Richard Langley 
<l...@unb.ca>
Sent: Sunday, January 29, 2017 7:02 PM
To: rodwall1...@gmail.com
Cc: sundial list
Subject: Re: Time question on GPS TIME and leap second.

Yes. The navigation message transmitted by GPS satellites includes the current 
leap second offset so a receiver can compute and display correct UTC.

-- Richard Langley

Sent from my iPhone

On Jan 29, 2017, at 6:05 PM, 
rodwall1...@gmail.com<mailto:rodwall1...@gmail.com> 
<rodwall1...@gmail.com<mailto:rodwall1...@gmail.com>> wrote:

Hi all,

Was just listening to the CrowdScience on time. Thanks to whoever posted the 
link to it.

CrowdScience indicated that a leap second was not added for the GPS. They also 
indicated that the GPS gives us UTC time.

Question:
The UTC time that the GPS gives. Does that have the leap second added?

Thanks,

Regards,

Roderick Wall.

- Reply message -
From: "Michael Ossipoff" <email9648...@gmail.com<mailto:email9648...@gmail.com>>
To: "Robert Kellogg" <rkell...@comcast.net<mailto:rkell...@comcast.net>>
Cc: "sundial list" <sundial@uni-koeln.de<mailto:sundial@uni-koeln.de>>
Subject: Why we should reform the Calendar
Date: Mon, Jan 30, 2017 8:00 AM


On Sun, Jan 29, 2017 at 2:41 PM, Robert Kellogg 
<rkell...@comcast.net<mailto:rkell...@comcast.net>>
wrote:

> Michael goes off looking for the ideal tropical year


There isn't an "ideal tropical year", but, as a choice for a
leapyear-rule's mean-year, the length of the mean tropical year (MTY) is
best for year-round reduction of longterm calendar-drift.  ...and the
average of the lengths of the March & September Equinox tropical years
(I'll call that the Average Equinox Year (AEY) ) is a compromise between
the vernal equinoxes of the North & the South.


> , perhaps ignoring effects of the earth's nutations.
>

Of course. The nutations are small in amplitude & period. They aren't part
of calendar rules. The mean equinox (nutations averaged-out) is the one
that is meant when the equinox is spoken of with regard to calendars.



> I'll still take the one of 1900, most importantly because it defines the
> SI second.


The SI second was defined as 1/86,400 of a mean solar day, for some year in
the early 19th century. I don't remember exactly what year that was. 1820?
1840? 1850?

Evidently it isn't practical to update the length of the SI second, but
that doesn't mean that calendars have to be based on the ephemeris day, or
atomic day, consisting of 86,400 SI seconds, when that's known to be
different from today's mean solar day.

That's why I suggest 365.24217 instead of 365.24219 for the length of the
mean tropical year (MTYI. It makes sense to base a calendar leap-year
rule's mean-year on the actual length of a tropical-year (whichever one we
want to use) on the length of that tropical year in* today's* mean days.


>
>
> So, contemplating changing the year is non trivial.


Evidently there must be some reason why it would be impractical to update
the length of the SI second. But it isn't necessary to call a MTY 365.24219
days, when it's really 365.24217 mean days long.   ...for the purposes of a
calendar leapyear rule. There's inevitable inaccuracy due to rounding-off,
and due to gradual change in the lengths of all the tropical years,
including the MTY. But that doesn't mean we have to intentionally add
avoidable error.



> Contemplating decoupling UTC from the rotation of the earth (ie necessity
> of being within .9 sec of UT1) likewise has significant consequences.
> Let's let the IAU chart the future of time.


Sure, but it isn't necessary to 

Re: Time question on GPS TIME and leap second.

[Richard Langley]

Yes. The navigation message transmitted by GPS satellites includes the current 
leap second offset so a receiver can compute and display correct UTC.

-- Richard Langley

Sent from my iPhone

On Jan 29, 2017, at 6:05 PM, 
rodwall1...@gmail.com<mailto:rodwall1...@gmail.com> 
<rodwall1...@gmail.com<mailto:rodwall1...@gmail.com>> wrote:

Hi all,

Was just listening to the CrowdScience on time. Thanks to whoever posted the 
link to it.

CrowdScience indicated that a leap second was not added for the GPS. They also 
indicated that the GPS gives us UTC time.

Question:
The UTC time that the GPS gives. Does that have the leap second added?

Thanks,

Regards,

Roderick Wall.

- Reply message -
From: "Michael Ossipoff" <email9648...@gmail.com<mailto:email9648...@gmail.com>>
To: "Robert Kellogg" <rkell...@comcast.net<mailto:rkell...@comcast.net>>
Cc: "sundial list" <sundial@uni-koeln.de<mailto:sundial@uni-koeln.de>>
Subject: Why we should reform the Calendar
Date: Mon, Jan 30, 2017 8:00 AM


On Sun, Jan 29, 2017 at 2:41 PM, Robert Kellogg 
<rkell...@comcast.net<mailto:rkell...@comcast.net>>
wrote:

> Michael goes off looking for the ideal tropical year


There isn't an "ideal tropical year", but, as a choice for a
leapyear-rule's mean-year, the length of the mean tropical year (MTY) is
best for year-round reduction of longterm calendar-drift.  ...and the
average of the lengths of the March & September Equinox tropical years
(I'll call that the Average Equinox Year (AEY) ) is a compromise between
the vernal equinoxes of the North & the South.


> , perhaps ignoring effects of the earth's nutations.
>

Of course. The nutations are small in amplitude & period. They aren't part
of calendar rules. The mean equinox (nutations averaged-out) is the one
that is meant when the equinox is spoken of with regard to calendars.



> I'll still take the one of 1900, most importantly because it defines the
> SI second.


The SI second was defined as 1/86,400 of a mean solar day, for some year in
the early 19th century. I don't remember exactly what year that was. 1820?
1840? 1850?

Evidently it isn't practical to update the length of the SI second, but
that doesn't mean that calendars have to be based on the ephemeris day, or
atomic day, consisting of 86,400 SI seconds, when that's known to be
different from today's mean solar day.

That's why I suggest 365.24217 instead of 365.24219 for the length of the
mean tropical year (MTYI. It makes sense to base a calendar leap-year
rule's mean-year on the actual length of a tropical-year (whichever one we
want to use) on the length of that tropical year in* today's* mean days.


>
>
> So, contemplating changing the year is non trivial.


Evidently there must be some reason why it would be impractical to update
the length of the SI second. But it isn't necessary to call a MTY 365.24219
days, when it's really 365.24217 mean days long.   ...for the purposes of a
calendar leapyear rule. There's inevitable inaccuracy due to rounding-off,
and due to gradual change in the lengths of all the tropical years,
including the MTY. But that doesn't mean we have to intentionally add
avoidable error.



> Contemplating decoupling UTC from the rotation of the earth (ie necessity
> of being within .9 sec of UT1) likewise has significant consequences.
> Let's let the IAU chart the future of time.


Sure, but it isn't necessary to base a calendar on a day that isn't today's
mean solar day.

Michael Ossipoff





> Dennis and Ken, if you're listening to this discussion, please chime in.
>
>
> On 1/29/2017 12:27 PM, 
> sundial-requ...@uni-koeln.de<mailto:sundial-requ...@uni-koeln.de> wrote:
>
>> Send sundial mailing list submissions to
>> sundial@uni-koeln.de<mailto:sundial@uni-koeln.de>
>>
>> To subscribe or unsubscribe via the World Wide Web, visit
>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>> or, via email, send a message with subject or body 'help' to
>> sundial-requ...@uni-koeln.de<mailto:sundial-requ...@uni-koeln.de>
>>
>> You can reach the person managing the list at
>> sundial-ow...@uni-koeln.de<mailto:sundial-ow...@uni-koeln.de>
>>
>> When replying, please edit your Subject line so it is more specific
>> than "Re: Contents of sundial digest..."
>>
>>
>> Today's Topics:
>>
>> 1. Re: Why we should reform the Calendar (Michael Ossipoff)
>>
>>
>> --
>>
>> Message: 1
>> Date: Sun, 29 Jan 2017 12:27:56 -0500
>> From: Michael Ossipoff 
>> <email9648...@gmail.com<mailto:email9648...@gmail.com>>
>> To: Dan-George Uza

What is the Real Time?

[Richard Langley]

An episode of the BBC World Service program "CrowdScience". A couple of 
inaccuracies/exaggerations but worth a listen.

"It sounds like a simple question – what is the time? But look closer and you 
realise time is a slippery concept that scientists still do not fully 
understand. Even though we now have atomic clocks that can keep time to one 
second in 15 billion years, this astonishing level of accuracy may not be 
enough. The complexity of computer-controlled systems, such as high-frequency 
financial trading or self-driving cars which rely on the pinpoint accuracy of 
GPS, could in future require clocks that are even more accurate to ensure 
everything runs ‘on time’.

"But what does that even mean? As Anand Jagatia discovers, time is a very 
strange thing. He visits the origins of modern time-keeping at the Royal 
Observatory in Greenwich and meets scientists at the National Physical 
Laboratory who have been counting and labelling every second since the 1950s. 
He meets Demetrios Matsakis, the man who defined time and visits the real-life 
‘Time Lords’, at the International Bureau of Weights and Measures (BIPM) in 
Paris to find out how they co-ordinate the world’s time and why the leap second 
is ‘dangerous’."

http://www.bbc.co.uk/programmes/p04q778b

-- Richard Langley

-
| Richard B. LangleyE-mail: l...@unb.ca |
| Geodetic Research Laboratory  Web: http://gge.unb.ca  |
| Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142   |
| University of New Brunswick   Fax:  +1 506 453-4943   |
| Fredericton, N.B., Canada  E3B 5A3|
|Fredericton?  Where's that?  See: http://www.fredericton.ca/   |
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Re: Leap Second Quiz Question

[Richard Langley]

The angular momentum of the Earth-moon system has to be conserved, so if the 
Earth's rotation slows more, then the moon speeds up in its orbit and moves 
further away from the Earth. Currently, as a result of the ongoing secular 
deceleration of the Earth (due to tidal friction), the moon moves about 2 cm 
further away each year. This was confirmed by lunar laser ranging -- an area I 
worked in for my postdoctoral studies way back when. Tidal friction is a 
primary reason for leap seconds, to bring us full circle. This is what I wrote 
for the previous leap second:

http://www2.unb.ca/gge/Resources/LeapSecond2015.pdf


-- Richard Langley


-
| Richard B. LangleyE-mail: l...@unb.ca |
| Geodetic Research Laboratory  Web: 
http://gge.unb.ca<http://gge.unb.ca/>  |
| Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142   |
| University of New Brunswick   Fax:  +1 506 453-4943   |
| Fredericton, N.B., Canada  E3B 5A3|
|Fredericton?  Where's that?  See: 
http://www.fredericton.ca/<https://unbmail.unb.ca/owa/redir.aspx?C=tVxi5OaRXE2jUmSNTu0wE7USusV6L9AIh-TKOqhq1DE--EjKeq-SUal8Myg-FGJn53Gm890SFIc.=http%3a%2f%2fwww.fredericton.ca%2f>
   |
-

From: sundial <sundial-boun...@uni-koeln.de> on behalf of Dave Bell 
<db...@thebells.net>
Sent: Sunday, January 1, 2017 2:24 PM
To: 'David'; sundial@uni-koeln.de
Subject: RE: Leap Second Quiz Question

Logically, tidal power should slow the Earth’s rotation.
Mechanical energy, imparted by the combined gravitation of the Sun and Moon is 
converted to electrical energy, then primarily dissipated as heat. Drag applied 
to the tidal surge must, to some extent, add drag to the Earth’s rotation.

Now, does the extracted energy also slow the Moon’s revolution about the Earth?

Dave

From: sundial [mailto:sundial-boun...@uni-koeln.de] On Behalf Of David
Sent: Sunday, January 1, 2017 7:19 AM
To: sundial@uni-koeln.de
Subject: Re: Leap Second Quiz Question

On 01/01/2017 12:30, Frank King wrote:

Dear All,



I hope you all enjoyed the extra second

in bed this morning and that your alarm

clock didn't go off one second early.



Here is an easy question to start off

the New Year...



Every Sunday at 08:00 I check the first

stroke of the hour-bell of the University

Clock against a radio-controlled UTC clock.



If it is slow I add coins to the tray on

the pendulum.  If it is fast I remove

coins.  My formula for the required

adjustment includes a figure for:



Last Week's Gain [LWG]



Here are my recent observations:



  25 December   clock 0.5 seconds fast

   1 Januaryclock 2.0 seconds fast



Is the appropriate figure for LWG:



a) 0.5 seconds

b) 1.5 seconds

c) 2.5 seconds



Frank



Frank H. King

Keeper of the University Clock

Cambridge, U.K.





---

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Dear Frank,

Happy New Year! I am sorry to hear that it starts with a problem for you albeit 
one of the horological kind, so that removes the pain.

I am somewhat puzzled, too.

You say:
Every Sunday at 08:00 I check the first stroke of the hour-bell of the 
University Clock against a radio-controlled UTC clock. If it is slow I add 
coins to the tray on the pendulum. If it is fast I remove coins.

Does the 'it' at the beginning of your second par. refer to the University 
clock?
If so, then if it is slow (i.e. rings after the UTC clock says it should), then 
its pendulum is too long (C.G. too low), so needs shortening. So coins need to 
be removed, not added. This assumes that the place where you add/remove the 
coins is below the current C.G.

As to the main question, between 25/12 and 1/1, the clock appears to have 
gained 1.5 s. But the UTC clock has added a second, so the University clock has 
gained only 0.5 s so the LWG is 0.5 s. In any case, if the clock has not been 
tampered with, it is unlikely that the University clock will have changed its 
previous LWG of 0.5 s to 1.5 or even 2.5 s in the space of a week. So I'll go 
for 0.5 s as the correct answer.
David.







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Re: Fw: Leap Second Quiz Question

[Richard Langley]

?Yes, perhaps 0.5 seconds is it. Last Sunday it was 0.5 seconds fast and Frank 
did something with the coins to change its rate. This Sunday it is 1 second 
fast, discounting the leap second. So, the clock gained an additional 0.5 
seconds in the week. Did I get it right this time? More/fewer coins needed? ;-)


-- Richard Langley


-
| Richard B. LangleyE-mail: l...@unb.ca |
| Geodetic Research Laboratory  Web: 
http://gge.unb.ca<http://gge.unb.ca/>  |
| Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142   |
| University of New Brunswick   Fax:  +1 506 453-4943   |
| Fredericton, N.B., Canada  E3B 5A3|
|Fredericton?  Where's that?  See: 
http://www.fredericton.ca/<https://unbmail.unb.ca/owa/redir.aspx?C=tVxi5OaRXE2jUmSNTu0wE7USusV6L9AIh-TKOqhq1DE--EjKeq-SUal8Myg-FGJn53Gm890SFIc.=http%3a%2f%2fwww.fredericton.ca%2f>
   |
-

From: Patrick Vyvyan <patrickvyv...@gmail.com>
Sent: Sunday, January 1, 2017 9:54 AM
To: Richard Langley
Subject: Re: Fw: Leap Second Quiz Question

0.5 seconds for me!

It's not exactly the fault of your clock's mechanism that due to the foibles of 
the IERS, the rules of the game have been changed. Every time a government 
decides to apply or remove DST, for example, I doubt you would say the clock 
had gained or lost 60 minutes?


Patrick Vyvyan
Presidente
Corporación Cultural de Putaendo
[http://banners.wunderground.com/cgi-bin/banner/ban/wxBanner?bannertype=wxstnsticker_both=IVALPARA7]

On 1 January 2017 at 10:17, Richard Langley <l...@unb.ca<mailto:l...@unb.ca>> 
wrote:
1.5 seconds? The clock is two seconds fast this morning due to its natural rate 
and the leap second. By the way, did anyone catch the seven pips live on BBC 
Radio 4 last night? Using the BBC's "listen again" feature, none of the other 
BBC radio stations carried the pips at midnight; they all (or mostly all) used 
Big Ben. And the listen again feature for Radio 4 just before midnight is a 
repeat of an earlier program when they announce the time as 5 p.m.!

-- Richard Langley

-
| Richard B. LangleyE-mail: 
l...@unb.ca<mailto:l...@unb.ca> |
| Geodetic Research Laboratory  Web: http://gge.unb.ca  |
| Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 
453-5142<tel:%2B1%20506%20453-5142>   |
| University of New Brunswick   Fax:  +1 506 
453-4943<tel:%2B1%20506%20453-4943>   |
| Fredericton, N.B., Canada  E3B 5A3|
|Fredericton?  Where's that?  See: http://www.fredericton.ca/   |
-


From: sundial 
<sundial-boun...@uni-koeln.de<mailto:sundial-boun...@uni-koeln.de>> on behalf 
of Frank King <f...@cl.cam.ac.uk<mailto:f...@cl.cam.ac.uk>>
Sent: Sunday, January 1, 2017 8:30 AM
To: sundial@uni-koeln.de<mailto:sundial@uni-koeln.de>
Subject: Leap Second Quiz Question

Dear All,

I hope you all enjoyed the extra second
in bed this morning and that your alarm
clock didn't go off one second early.

Here is an easy question to start off
the New Year...

Every Sunday at 08:00 I check the first
stroke of the hour-bell of the University
Clock against a radio-controlled UTC clock.

If it is slow I add coins to the tray on
the pendulum.  If it is fast I remove
coins.  My formula for the required
adjustment includes a figure for:

Last Week's Gain [LWG]

Here are my recent observations:

  25 December   clock 0.5 seconds fast
   1 Januaryclock 2.0 seconds fast

Is the appropriate figure for LWG:

a) 0.5 seconds
b) 1.5 seconds
c) 2.5 seconds

Frank

Frank H. King
Keeper of the University Clock
Cambridge, U.K.


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---
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Fw: Leap Second Quiz Question

[Richard Langley]

1.5 seconds? The clock is two seconds fast this morning due to its natural rate 
and the leap second. By the way, did anyone catch the seven pips live on BBC 
Radio 4 last night? Using the BBC's "listen again" feature, none of the other 
BBC radio stations carried the pips at midnight; they all (or mostly all) used 
Big Ben. And the listen again feature for Radio 4 just before midnight is a 
repeat of an earlier program when they announce the time as 5 p.m.!

-- Richard Langley

-
| Richard B. LangleyE-mail: l...@unb.ca |
| Geodetic Research Laboratory  Web: http://gge.unb.ca  |
| Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142   |
| University of New Brunswick   Fax:  +1 506 453-4943   |
| Fredericton, N.B., Canada  E3B 5A3|
|Fredericton?  Where's that?  See: http://www.fredericton.ca/   |
-


From: sundial <sundial-boun...@uni-koeln.de> on behalf of Frank King 
<f...@cl.cam.ac.uk>
Sent: Sunday, January 1, 2017 8:30 AM
To: sundial@uni-koeln.de
Subject: Leap Second Quiz Question

Dear All,

I hope you all enjoyed the extra second
in bed this morning and that your alarm
clock didn't go off one second early.

Here is an easy question to start off
the New Year...

Every Sunday at 08:00 I check the first
stroke of the hour-bell of the University
Clock against a radio-controlled UTC clock.

If it is slow I add coins to the tray on
the pendulum.  If it is fast I remove
coins.  My formula for the required
adjustment includes a figure for:

Last Week's Gain [LWG]

Here are my recent observations:

  25 December   clock 0.5 seconds fast
   1 Januaryclock 2.0 seconds fast

Is the appropriate figure for LWG:

a) 0.5 seconds
b) 1.5 seconds
c) 2.5 seconds

Frank

Frank H. King
Keeper of the University Clock
Cambridge, U.K.


---
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---
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Re: Permanent DST

[Richard Langley]

"Daylight saving time can decrease the frequency of wildlife–vehicle 
collisions" by
William A. Ellis, Sean I. FitzGibbon, Benjamin J. Barth, Amanda C. Niehaus, 
Gwendolyn K. David, Brendan D. Taylor, Helena Matsushige, Alistair Melzer, Fred 
B. Bercovitch, Frank Carrick, Darryl N. Jones, Cathryn Dexter, Amber Gillett, 
Martin Predavec, Dan Lunney, Robbie S. Wilson
Biology Letters, November 2016, Volume 12, issue 11, DOI: 10.1098/rsbl.2016.0632

Abstract

Daylight saving time (DST) could reduce collisions with wildlife by changing 
the timing of commuter traffic relative to the behaviour of nocturnal animals. 
To test this idea, we tracked wild koalas (Phascolarctos cinereus) in southeast 
Queensland, where koalas have declined by 80% in the last 20 years, and 
compared their movements with traffic patterns along roads where they are often 
killed. Using a simple model, we found that DST could decrease collisions with 
koalas by 8% on weekdays and 11% at weekends, simply by shifting the timing of 
traffic relative to darkness. Wildlife conservation and road safety should 
become part of the debate on DST.

-- Richard Langley

P.S. Sorry to prolong the debate, which is only periferally related to 
sundials, but this article (I am not a biologist) just came to my attention.

-
| Richard B. LangleyE-mail: l...@unb.ca |
| Geodetic Research Laboratory  Web: http://gge.unb.ca/ |
| Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142   |
| University of New Brunswick   Fax:  +1 506 453-4943   |
| Fredericton, N.B., Canada  E3B 5A3|
|Fredericton?  Where's that?  See: http://www.fredericton.ca/   |
-



> On Nov 25, 2016, at 2:31 PM, Douglas Bateman <douglas.bate...@btinternet.com> 
> wrote:
> 
> Dear Barbara and Augustine,
> 
> I am flattered that you are following this dialogue, and I’m sure Frank is 
> too.
> 
> Frank wishes to wind up the discussion, and this can be my final, and 
> personal, contribution.
> 
> First of all, it is obvious that Frank is both happy to be a very early riser 
> and is prepared to challenge any topic and any assumptions. For example the 
> ‘effective day centred on 3pm’.
> 
> If I rise very early in the summer, I may be enthralled by a sunrise or quiet 
> dawn (and wonder if this is the best part of the day). However, I like to 
> have 8 hours of sleep, AND enjoy long summer evenings, glass in hand. It 
> follows that for most days, I am prepared to sacrifice the early hours, and 
> therefore my day may run from 7am to 10 or 11pm.  3pm is therefore a nominal 
> middle of the waking day. Society in the UK as a whole seems happy with this, 
> and is the basic reason for daylight saving time.
> 
> When winter approaches, the clocks are put back with many grumbles about the 
> darker evenings. Without delving into accident statistics, it is obvious that 
> the risks to school children walking or cycling home in the dark are 
> increased. It is equally obvious that motorists driving home in the dark 
> after a tiring day, and impatient to be home, increase the risks as well, 
> both to themselves and others.
> 
> I’m sure that these opinions, and similar, may have have caused some 
> countries to adopt DST on a permanent basis.
> 
> Ultimately we can define time to be whatever we want it to be, and even 
> ignore the historical convention of noon when the sun is due south, even if 
> this offends some of the sundial enthusiasts.
> 
> Glad to know you have enjoyed the fun, even if there is a serious element.
> 
> Best wishes, Doug
> 
> 
>> On 25 Nov 2016, at 14:41, Barbara and Augustine McCaffrey 
>> <mccaffre...@gmail.com> wrote:
>> 
>> Please, I am enjoying and learning from the discussion, so I would prefer 
>> that it continue where I may read it.  Many thanks.  
>> 
>> On Fri, Nov 25, 2016 at 3:22 PM, Frank King <f...@cl.cam.ac.uk> wrote:
>> Dear Doug,
>> 
>> It is probably time to conclude this
>> fascinating discussion so this will
>> be my final public offering (for a
>> while).
>> 
>> > A significant part of my note is
>> > reporting the work of others...
>> 
>> Indeed so.  I am familiar with most
>> of your citations, especially, the
>> report by the Cambridge Engineers.
>> The methodology used was an utter
>> disgrace in my view.
>> 
>> It is exceptionally difficult to
>> find a way of comparing like with
>> like without getting biased results.
>> Also, 

Re: Sundial Puzzle Corner

[Richard Langley]

"As far as I know, these days, this
subject isn't taught ANYWHERE in
the UK even in Universities.

Geometry is deemed a useless subject
because 'you don't really need it'."

Might be taught in geomatics programs in the U.K. We certainly teach it in our 
own courses as well as a bespoke course from the Math and Stats Department:
http://www2.unb.ca/gge/Study/Undergraduate/CourseSequence.pdf
http://www.unb.ca/academics/calendar/undergraduate/current/frederictoncourses/mathematics/math-3543.html

-- Richard Langley

-
| Richard B. LangleyE-mail: l...@unb.ca |
| Geodetic Research Laboratory  Web: http://gge.unb.ca/ |
| Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142   |
| University of New Brunswick   Fax:  +1 506 453-4943   |
| Fredericton, N.B., Canada  E3B 5A3|
|Fredericton?  Where's that?  See: http://www.fredericton.ca/   |
-



> On Oct 31, 2016, at 5:50 AM, Frank King <f...@cl.cam.ac.uk> wrote:
> 
> Dear Karl,
> 
> Your idea is not without merit:
> 
>> Wrap the slate with a reflective strip ...
>> Playing around with a laser should find the
>> focii.
> 
> This is sometimes referred to as the
> "Elliptical Billiard Table Problem"...
> 
> If you aim at a focus, the laser path will
> reflect through the other focus and so on.
> Eventually it will settle down into
> running backwards and forwards along the
> major axis BUT...
> 
> If you aim the laser so that its path
> passes OUTSIDE the line joining the
> two foci, the path traced will, after
> an indefinite number of reflections,
> leave a dead area in the centre which
> is ITSELF an ellipse.
> 
> If you aim the laser so that its path
> passes BETWEEN the two foci, the path
> traced will, after an indefinite number
> of bounces, leave two dead areas around
> each end of the major axis.  The inner
> boundaries of these areas are the turning
> points of a hyperbola.
> 
> The real excitement comes if you aim
> the laser so that you get a return to
> the starting point after a finite
> number of reflections.
> 
> You then get a nice pretty pattern.  I
> have knocked up the attached example
> where there are 46 reflections.
> 
> You can prove all this using
> Projective Geometry.  This is a
> delightful subject which includes
> splendid concepts such as "The
> Circular Points at Infinity".
> 
> In the 1950's, Projective Geometry
> was in the UK A-level Mathematics
> syllabus and taught to 17- and
> 18-year olds.
> 
> As far as I know, these days, this
> subject isn't taught ANYWHERE in
> the UK even in Universities.
> 
> Geometry is deemed a useless subject
> because "you don't really need it".
> 
> End of rant.
> 
> Frank
> 
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
> 

---
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Re: My sundial books

[Richard Langley]

Hi Hal:
Where are you located?
-- Richard Langley
   University of New Brunswick

Sent from my iPhone

On Sep 17, 2016, at 9:27 AM, Hals Email 
<hal2d...@gmail.com<mailto:hal2d...@gmail.com>> wrote:

I need some suggestions from the sundial list.  I would like to donate my 
sundial book library of over 100 books, with an estimated value of at least 
$1000.  I have enjoyed using them but now would like to donate them as a unit 
to a college or university library.  However, the recipient would be expected 
to pay shipping costs.  If you have suggestions for a contact I can mail a list 
of these books.

Thank you for your help,

Hal Brandmaier


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Re: Amira Willighagen

[Richard Langley]

Google and ye shall find:
https://en.wikipedia.org/wiki/Amira_Willighagen

-
| Richard B. LangleyE-mail: l...@unb.ca |
| Geodetic Research Laboratory  Web: http://gge.unb.ca/ |
| Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142   |
| University of New Brunswick   Fax:  +1 506 453-4943   |
| Fredericton, N.B., Canada  E3B 5A3|
|Fredericton?  Where's that?  See: http://www.fredericton.ca/   |
-



> On Jun 4, 2016, at 3:53 PM, Richard Mallett  
> wrote:
> 
> On 23/05/2016 10:09, tonylindi...@talktalk.net wrote:
>> Hi,
>>  If you are a 'Sundial Messages Only' person PLEASE IGNORE THIS.  For 
>> the rest of us here are a few moments of pure and absolute delight (Sound on)
>> 
>> www.youtube.com/embed/ZWpLfncliwU?rel=0
>> 
>> 
>> Tony Moss
>> 
>> 
>> ---
>> 
>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>> 
>> 
>> 
> 
> My first thought was that she was miming, but she clearly was not.  I see 
> that this was dated 2013 - I wonder what she has done   in the three 
> years since then ?
> -- 
> --
> Richard Mallett
> Eaton Bray, Dunstable
> South Beds. UK
> 
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
> 

---
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Re: Amira Willighagen

[Richard Langley]

Thanks, Tony. As one of the judges said at the end of the video, "f***ing 
amazing." Hadn't heard of her before. More here: 
https://en.wikipedia.org/wiki/Amira_Willighagen?

Thanks again.

-- Richard Langley


-
| Richard B. LangleyE-mail: l...@unb.ca |
| Geodetic Research Laboratory  Web: 
http://gge.unb.ca<http://gge.unb.ca/>  |
| Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142   |
| University of New Brunswick   Fax:  +1 506 453-4943   |
| Fredericton, N.B., Canada  E3B 5A3|
|Fredericton?  Where's that?  See: 
http://www.fredericton.ca/<https://unbmail.unb.ca/owa/redir.aspx?C=tVxi5OaRXE2jUmSNTu0wE7USusV6L9AIh-TKOqhq1DE--EjKeq-SUal8Myg-FGJn53Gm890SFIc.=http%3a%2f%2fwww.fredericton.ca%2f>
   |
-

From: sundial <sundial-boun...@uni-koeln.de> on behalf of 
tonylindi...@talktalk.net <tonylindi...@talktalk.net>
Sent: Monday, May 23, 2016 6:09 AM
To: Sundial List Sundial List
Subject: Amira Willighagen

Hi,
 If you are a 'Sundial Messages Only' person PLEASE IGNORE THIS.  For the 
rest of us here are a few moments of pure and absolute delight (Sound on)

www.youtube.com/embed/ZWpLfncliwU?rel=0<http://www.youtube.com/embed/ZWpLfncliwU?rel=0>


Tony Moss
---
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An Interesting Article on Natural Timekeeping

[Richard Langley]

Villages Must Recalibrate Time to Survive in the Pamir Mountains

Scientists plan projects this year to help a rugged, troubled region of central 
Asia retune traditional timekeeping methods based on environmental cues in the 
face of climate change.

More:
https://eos.org/agu-news/villages-must-recalibrate-time-to-survive-in-the-pamir-mountains

-- Richard Langley

-
| Richard B. LangleyE-mail: l...@unb.ca |
| Geodetic Research Laboratory  Web: http://gge.unb.ca  |
| Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142   |
| University of New Brunswick   Fax:  +1 506 453-4943   |
| Fredericton, N.B., Canada  E3B 5A3|
|Fredericton?  Where's that?  See: http://www.fredericton.ca/   |
-
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Re: Sundials near the Equator

[Richard Langley]

There is the huge Quitsato Sundial near Quito. If you Google "Quitsato Sundial" 
and select Images, you'll find some with people in them.
-- Richard Langley

-
| Richard B. LangleyE-mail: l...@unb.ca |
| Geodetic Research Laboratory  Web: http://gge.unb.ca  |
| Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142   |
| University of New Brunswick   Fax:  +1 506 453-4943   |
| Fredericton, N.B., Canada  E3B 5A3|
|Fredericton?  Where's that?  See: http://www.fredericton.ca/   |
-


From: sundial <sundial-boun...@uni-koeln.de> on behalf of David 
<da...@davidbrownsundials.com>
Sent: Thursday, March 24, 2016 9:20 AM
To: sundial
Subject: Sundials near the Equator

Dear fellow shadow-watchers...

Can anyone direct me to images of large sundials near to the Equator,
preferably with some element of human involvement?

David Brown
Somerton, Somerset UK

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Re: It's still summer in Sydney (or is it?)

[Richard Langley]

Meteorologists do have a different view (for computational purposes):
http://www.rin.org.uk/newsitem/4457/Farewell-Winter
-- Richard Langley

-
| Richard B. LangleyE-mail: l...@unb.ca |
| Geodetic Research Laboratory  Web: http://gge.unb.ca  |
| Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142   |
| University of New Brunswick   Fax:  +1 506 453-4943   |
| Fredericton, N.B., Canada  E3B 5A3|
|Fredericton?  Where's that?  See: http://www.fredericton.ca/   |
-


From: sundial <sundial-boun...@uni-koeln.de> on behalf of John Pickard 
<john.pick...@bigpond.com>
Sent: Sunday, March 6, 2016 6:52 PM
To: Sundial List
Subject: It's still summer in Sydney (or is it?)

Good morning all (and especially those in the Northern Hemisphere still
stuck in winter),

The following letter appeared in the Sydney Morning Herald (Saturday 5 March
2016, p. 39)

"Still summer in Sydney.

It's hard not to be amused by the apparently genuine surprise expressed this
past week - mainly by television weather presenters - at the high
temperatures being recorded around the country 'in the first week of
autumn'. I'm not sure which authority declared that autumn starts on March
1; however the change of seasons is an immutable astronomical event
resulting from a shift in the earth's axis each three months on the two
equinoxes and the two solstices, which coincide with the human invented
calendar dates of (approximately) March and September 21; and June and
December 21. So it has not been an amazingly hot start to "autumn'; it is
still summer and will be for nearly three more weeks.

Martyn Yeomans, St Ives."


Relying on TV weather presenters for anything other than a forecast taken
directly from the Australian Bureau of Meteorology (in our case) is a bit
silly. TV presenters are selected on their good looks (that's why I didn't
make it!), laser-whitened teeth, and their ability to smile while talking
under wet cement. They are never selected on their knowledge of anything.

And yes, it is still summery here, temperatures in high 20s, wall-to-wall
blue sky. Lovely!

Cheers, John

Dr John Pickard
john.pick...@bigpond.com

In a VERY sunny Sydney.

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Re: longest uninterupted meridian line in the world

[Richard Langley]

?I suppose it depends on what "uninterrupted" means. Of course, there is the 
famous Paris meridian line starting at the observatory that goes for many km 
but outside the observatory grounds, it is only marked by medallions here and 
there I think. And I forget (I have been there) whether on the observatory 
grounds there is a continuous strip or something similar.

-- Richard Langley


-
| Richard B. LangleyE-mail: l...@unb.ca |
| Geodetic Research Laboratory  Web: 
http://gge.unb.ca<http://gge.unb.ca/>  |
| Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142   |
| University of New Brunswick   Fax:  +1 506 453-4943   |
| Fredericton, N.B., Canada  E3B 5A3|
|Fredericton?  Where's that?  See: 
http://www.fredericton.ca/<https://unbmail.unb.ca/owa/redir.aspx?C=tVxi5OaRXE2jUmSNTu0wE7USusV6L9AIh-TKOqhq1DE--EjKeq-SUal8Myg-FGJn53Gm890SFIc.=http%3a%2f%2fwww.fredericton.ca%2f>
   |
-

From: sundial <sundial-boun...@uni-koeln.de> on behalf of Willy Leenders 
<willy.leend...@telenet.be>
Sent: Wednesday, December 9, 2015 2:15 PM
To: Sundial sundiallist
Subject: longest uninterupted meridian line in the world

Hj all,

In a herb garden in Hasselt (Belgium) is a meridian line of 90 meters.
At one end it is enclosed by a analematic sundial.
The meridian line will be extended to 230 meters
Does anyone know a uninterupted meridian line that is longer than 200 meters?
There are plans to propose placing the meridian line in Guinness World Records.

Willy Leenders
Hasselt in Flanders (Belgium)

Visit my website about the sundials in the province of Limburg (Flanders) with 
a section 'worth knowing about sundials' (mostly in Dutch): 
http://www.wijzerweb.be


[cid:CD7BA241-D1ED-4A16-92E1-E22279165135@home]

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Re: How to force spreadsheet to create printable graph with same scale in X and Y?

[Richard Langley]

Hi Steve:
It's one of the reasons why I prefer to use gnuplot, rather than  
Excel, for some plotting tasks. Gnuplot is dead easy to use and comes  
in different flavours for different operating systems:

http://www.gnuplot.info/
-- Richard

On 21-Jun-11, at 8:29 PM, Steve Lelievre wrote:


Hi,

I sometimes use a spreadsheet to calculate a series of X,Y points,  
and then use these points to create a scattergram chart. My problem  
is that whenever I do this, the chart appears on the screen as a  
rectangle. The X and Y dimensions aren't to the same scale. I have  
to set the gridline intervals to be the same for X and Y and then  
adjust the chart so that the shape looks OK on screen.


My problem is that even if the chart grid appears to be in good  
proportion on the screen, it's only as good as my eyes. What I  
really want is to print an accurate diagram that I can use as an  
experimental dial. In short, I want the printed chart to be on a  
square grid that is really square.


Can anyone explain to me how to force the spreadsheet software to  
use absolute distances for a printed chart's axes? Alternatively, a  
way to force equal gridline spacing would be equally as helpful.


I use both OpenOffice and Excel - an answer for either one will be  
much appreciated.


Cheers,
Steve




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-
| Richard B. LangleyE-mail:  
l...@unb.ca |
| Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/ 
 |
| Dept. of Geodesy and Geomatics EngineeringPhone:+1 506  
453-5142   |
| University of New Brunswick   Fax:  +1 506  
453-4943   |
| Fredericton, N.B., Canada  E3B  
5A3|
|Fredericton?  Where's that?  See: http:// 
www.fredericton.ca/   |

-

---
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Re: bad sundials

[Richard Langley]

Included in the bad sundials list should be sundials, which were  
properly constructed for the location but improperly installed or  
improperly re-installed after cleaning or refurbishment. I happened to  
notice one I think falls in the latter category on the way to the  
terminal at Heathrow Airport last week. When the Hoppa bus stopped  
at the Renaissance Hotel off Bath Road (on the airport or south side),  
looking out the bus window, I noticed their sundial in the small  
garden in front of the main entrance. This is an equatorial dial. The  
gnomon does not point to the NCP. It points to the south and looks  
like the whole sundial needs to be rotated 180 degrees about the  
vertical. I didn't have time to get out and look at it more closely  
but I suspect there are four symmetrical mounting bolts and the  
sundial installer just plunked it down in the first orientation that  
fitted the bolts. Or some such mounting problem. The picture on their  
website seems to have the correct orientation judging by the direction  
of the shadow of the whole sundial.

http://www.marriott.co.uk/hotels/photo-tours.mi?marshaCode=lhrbrpageID=HWHOMimageID=2
Has anyone else noticed this bad sundial? Or reported it to the  
hotel? Pictures taken from inside the bus available on request.
-- Richard  


-
| Richard B. LangleyE-mail:  
l...@unb.ca |
| Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/ 
 |
| Dept. of Geodesy and Geomatics EngineeringPhone:+1 506  
453-5142   |
| University of New Brunswick   Fax:  +1 506  
453-4943   |
| Fredericton, N.B., Canada  E3B  
5A3|
|Fredericton?  Where's that?  See: http:// 
www.fredericton.ca/   |

-

---
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Re: upside down world

[Richard Langley]

The Catholic Encyclopedia has an interesting article on church  
orientation, including a mention of St. Peter's: http://en.wikisource.org/wiki/Catholic_Encyclopedia_%281913%29/Orientation_of_Churches 
.

-- Richard

On 19-Feb-11, at 11:47 AM, Frank King wrote:


Dear Jackie,

That is an interesting observation...


... I moved from London to Brighton...
In London it seemed usual to say it's on
the left of the street, but here on the
coast, far more people say it's on the
east side.


Next time I am in Brighton I shall test the
natives.

The natives here in Cambridge would almost all
fail.  When making arrangements to meet someone
I used to give instructions of the form I'll
meet you at the WEST door of a certain church.
This never worked and I eventually gave up when
even the Vicar went to the wrong door.

The church in question is properly orientated
with the west end very closely aligned with
due west so there is no excuse!

It has always intrigued me that S. Peter's,
Rome (which is arguably quite an important
church!) is almost exactly 180 degrees wrong
with the west front facing east!  Take a
look via Google Earth or Google Maps.

That wouldn't matter too much, but the obelisk
in S. Peter's Square is used as a noon mark.

The relevant markings are set out in the pavement
on the north side of the obelisk (as expected)
but when standing on the west front of the
church looking out across the square, the noon
shadow is to the left not to the right.

I am not sure I would be able to find the right
door there!

Frank

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-
| Richard B. LangleyE-mail:  
l...@unb.ca |
| Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/ 
 |
| Dept. of Geodesy and Geomatics EngineeringPhone:+1 506  
453-5142   |
| University of New Brunswick   Fax:  +1 506  
453-4943   |
| Fredericton, N.B., Canada  E3B  
5A3|
|Fredericton?  Where's that?  See: http:// 
www.fredericton.ca/   |

-

---
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Re: Sundial Information

[Richard Langley]

And I think Frank might be having us on with the owla  
interpretation. More likely the owls around Hughes Hall descend from  
the college's crest/shield:
http://en.m.wikipedia.org/wiki/Hughes_Hall%2C_Cambridge?wasRedirected=true 
.


-- Richard Langley

Sent from my iPod Touch


On 2010-11-19, at 1:06 PM, Frank King frank.k...@cl.cam.ac.uk wrote:


Dear John,


I'm asking you guys if you have seen any
relationship between owls and sundials.


I once tried very hard to establish such a
relationship but my best intentions were
not appreciated...

I had a client and I wanted to symbolise
sunrise and sunset on the proposed sundial.

I offered a really beautiful cock for sunrise
and an even more beautiful owl for sunset.

The client's comment was brief: too fussy.

So there was another good idea that failed
to see the light of day :-(

Actually there is a College in Cambridge,
Hughes Hall, which has a modern down-market
sundial and I am pretty sure there is an owl
on it.  That's because Hughes Hall in Latin
is Aula de Hughes and Aula sounds almost
like Owl and they have owls all over the
place in consequence.

OK, I'm just the messenger!

Very best wishes

Frank

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Canadian Maritimes POI File for Sundial Tourists

[Richard Langley]

I have created a point-of-interest file containing the geodetic coordinates
and brief descriptions of some of the sundials in New Brunswick and Nova
Scotia, two of the Canadian Maritime Provinces. The initial sources of
information were Steve Lelievre's Nova Scotia Sundial Trail
http://users.eastlink.ca/~srgl/trail.htm and the NASS Sundial Register
http://www.sundials.org/ plus various online mapping and other resources.

The text file has been created in a format which allowed conversion to a
TomTom Navigator software POI overlay file (with suffix .ov2). See
http://www.tomtom.com/support/ce/support/nav_poi.php for more
information.

The text file is easily read and could be converted to other GPS navigator
POI or waypoint file formats.

Attached are the small text and .ov2 files and a BMP icon which could be used
with the .ov2 file.

It would be useful for those of us who like visiting sundials on our vacations
to have sundial POI files for other regions. What is needed are accurate
WGS84 coordinates for the sundials or exact street addresses which can be
mapped to the coordinates.

-- Richard Langley

===
 Richard B. LangleyE-mail: [EMAIL PROTECTED]
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142
 University of New Brunswick   Fax:  +1 506 453-4943
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
===; Sundials in NB and NS Points-of-Interest (POI) Text File for TomTom Navigator

; Use MAKEOV2.EXE to create .ov2 file

; Created by Richard B. Langley, University of New Brunswick, 19 November 2005

; Longitude,Latitude, Name

; ==  




 -66.64093 ,   45.96205 , Vertical Wall Dial, Soldiers' Barracks, Fredericton, 
NB

 -64.21009 ,   45.83530 , Pedestal Dial, Amherst Town Hall, Amherst, NS

 -65.51581 ,   44.74222 , Pedestal Dial, Historic Gardens, Annapolis Royal, NS

 -64.24157 ,   44.53653 , Armillary Sphere, Parade Square, Chester, NS

 -64.30942 ,   45.11077 , Horizontal Dial, Acadian Memorial Church, Grand-Pré, 
NS

 -63.57431 ,   44.64362 , Armillary Sphere, DalTech, Halifax, NS

 -63.57855 ,   44.64317 , Horizontal Dial, Halifax Public Gardens, Halifax, NS

 -63.61490 ,   44.67549 , Horizontal Dial, Seaview Memorial Park, Halifax, NS

 -63.59218 ,   44.63629 , Pedestal Dial, Quadrangle, Dalhousie University, 
Halifax, NS

 -65.11979 ,   44.87788 , Pedestal Dial, Whitman Cemetary, Williamstown, NS

 -59.98763 ,   45.88903 , Pedestal Dial, Engineer's House, Fortress of 
Louisbourg, NS

 -65.07110 ,   44.94378 , Horizontal Dial, Macdonald Museum, Middleton, NS

 -63.83432 ,   44.89625 , Pedestal Dial, Uniacke Estate Museum Park, Mt. 
Uniacke, NS

 -64.37803 ,   45.11619 , Pedestal Dial, Prescott House Museum, Starr's Point, 
NS

 -64.13907 ,   44.98952 , Pedestal Dial, Haliburton House Museum, Windsor, NS

 -66.11557 ,   43.83651 , Portable Dial, Yarmouth County Museum, Yarmouth, NS



sundials.ov2
Description: Binary data


sundials.bmp
Description: Binary data
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Sundial Motif to Be Featured on New Canadian $10 Coin

[Richard Langley]

A Canadian $10 silver coin to be launched today celebrating the Fortress of
Louisbourg includes sundial numerals along its circumference alluding to the
sundial that was found during an archaeological dig at the historic sight.
A PDF flyer describing the coin is available on request or you can find it on
the Royal Canadian Mint Web site.
-- Richard Langley

===
 Richard B. LangleyE-mail: [EMAIL PROTECTED]
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142
 University of New Brunswick   Fax:  +1 506 453-4943
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
===
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Re: church interior dial

[Richard Langley]

There is an interesting article on the stations of the cross -- and variations
and dates in churches -- in the catholic encyclopedia:
http://www.newadvent.org/cathen/15569a.htm
-- Richard Langley

On Thu, 11 May 2006, Frans W. Maes wrote:

Hi Frank,

In Roman Catholic churches I noted always 14 Stations, numbered I-XIV.
Generally, they are placed symmetrically along the walls of the nave, thus
nr. I-VII on one side and VIII-XIV on the other.

Regards,
Frans Maes

- Original Message -
From: Frank Evans [EMAIL PROTECTED]
To: Sundial sundial@rrz.uni-koeln.de
Sent: Wednesday, May 10, 2006 5:10 PM
Subject: church interior dial


 Greetings fellow dialists,
 This is not really off topic, more off centre, perhaps. The church at
 Dalton-le-Dale, County Durham, England has what until now has been
 thought two dials. One is an important Anglo-Saxon dial of around 700
 AD, mounted on a later wall. The other, the object of my question, is a
 series of numbers on the inside north wall of the nave of this
 thirteenth century church.

 Mrs. Gatty describes them incorrectly: There are some remains of a dial
 on an interior wall of St. Andrew's Church at Dalton-le-Dale; only the
 numerals I to VII are to be seen now, and these are raised in relief
 upon the plaster, and are said to conceal an older set of figures. The
 hours would be shown when the sun shone through the south window.

 There is a story currently told that the sun shone on the easternmost
 number on St. Andrew's saint's day, 30 November from a former hole in
 the roof. Given the low angle of the noon sun on that day this is quite
 impossible

 The numerals on the north wall of the nave are in fact VII to XII, not I
 to VII, arranged linearly from west to east and occupy most of the
 length of the wall at a height of about a metre. They were viewed by
 members of the British Sundial Society during their meeting in Durham a
 few weeks ago and the general consensus was that the numbers could not
 be any form of time measure. A proposal was that they had been placed
 under successive Stations of the Cross pictures and that they had
 survived where the pictures and the numbers I to VI on the south wall
 had not.

 My question is this: What is the history of Stations of the Cross in the
 Church of England. Presumably some must be pre-Reformation but they
 would generally have been extinguished by Cromwell's men and the puritan
 movement. Could the numbers have survived, without pictures, from the
 seventeenth century and a gradual story have grown up about their
 representing a sort of sundial?

 Speculation welcome.
 Frank 55N 1W





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===
 Richard B. LangleyE-mail: [EMAIL PROTECTED]
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142
 University of New Brunswick   Fax:  +1 506 453-4943
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
===
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: mean time

[Richard Langley]

And here is a discussion of mean time as well as UTC:
http://gauss.gge.unb.ca/GMT.UT.and.the.RGO.html.
-- Richard Langley

On Sat, 11 Jun 2005, Gordon Uber wrote:

 From Explanatory Supplement to the Astronomical Almanac by Seidelmann,
pp. 74-6:

However, the sun's motion in right ascension [along the celestial equator]
is not uniform because the Sun moves in the ecliptic rather than the
equator, and the Sun's motion in the ecliptic is not uniform [due to
elliptical orbit].

Mean solar time was defined by an abstract fiducial point ... fictitious
mean sun ... to move uniformly in the equatorial plane at a rate that is
virtually equal to the mean rate of the true Sun's motion in the ecliptic.
The difference between mean solar time and apparent solar time is called
the equation of time.

At least formerly, solar time was computed from observed sidereal [star]
time. What is today called Greenwich Mean Time (civil time) in the UK is
actually Coordinated Universal Time for the Greenwich time zone. It is kept
by atomic clocks and modified by leap seconds as required by variations in
the Earth's rotation.

I am guessing that the observed noon (sun due south or at its highest
altitude) defined 12:00 noon for apparent solar time at Greenwich.

For those interested in this topic, this book has a sixty-page chapter on
time, including its history.

 From Astronomical Algorithms by Jean Meeus, p. 379, The mean solar time
is the hour angle of the mean sun , and this is measured from mean noon.
The civil time is the mean solar time increased by 12 hours, and thus is
measured from mean midnight.

Gordon


At 11:42 6/10/05, Noam Kaplan wrote:
Does anyone know how mean time is set up?

To clarify, I know that local mean time has 24 hours every day set for a
mean daily rotation for any particular location. I understand that
timezones are set up by the local mean time for the center of every 15
degrees of  longitude, i.e. 0, 15, 30, 45 etc.

What I don't understand is how was it chosen when 12:00 AM/PM would be.
I used to think that mean time was set by the equinox that midday was
12:00 for the whole year. This is obviously incorrect as the equation of
time which shows how much local mean time is off from apparent solar time
is not 0 at 12 on the equinox.

If anybody can explain to me what and how mean time was set up, I would
appreciate it.

Thanks,
Noam Kaplan
N 40.5833   W 74.1166
Staten Island


-



===
 Richard B. LangleyE-mail: [EMAIL PROTECTED]
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142
 University of New Brunswick   Fax:  +1 506 453-4943
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
===
-

Re: Which longitude/latitude to use?

[Richard Langley]

UT1 is definitively established by the IERS (now called the International
Earth Rotation and Reference Systems Service). UT1 is referenced to the ITRF
(the International Terrestrial Reference Frame) which is basically a set of
points whose coordinates realize the ideal International Terrestrial Reference
System (ITRS) There can be many realizations of the ITRS -- WGS84 is another
one. Over the years, WGS84 has been adjusted to move closer to the ITRF which
has turned out to be a better realization of the IERS.
The longitude origin of the ITRS is that which was initially given by the
forerunner of the IERS, the Bureau International de l'Heure (BIH) at the epoch
1984.0. For some background on the relationship between the BIH zero meridian
and that of the Airy transit circle at Greenwich, see this interesting Web
page: http://www.nmm.ac.uk/server/show/conWebDoc.416.
By the way, the U.S. military probably no longer has a better model of the
Earth's gravity field than that of the civilian community. The gravity model
which accompanies WGS84 was fully declassified in the early 1990s.
Subsequently, U.S. DoD worked with the U.S. National Geodetic Survey and NASA
to produce the superior and publicly available Earth Gravity Model 1996. This
is a global model. There are regional models of different parts of the Earth
which are even better.

-- Richard Langley

On Tue, 24 May 2005, Frank King wrote:

Dear Wee-Meng

You raise some very interesting points...

 When I read about longitudes/latitudes in GPS articles,
 there are loads of different types of projection used.

Indeed there are.  These all represent different models
of the shape of the Earth and the best one is kept secret
by the U.S. Military who probably know the shape of the
Earth better than anyone else!

 In my GPS, if a point is specified using the wrong
 projection, it may be way off.

Sadly this is true.  We in the U.K. like to think that
Longitude 0 degrees has been fixed since 1884 by the
position of Airy's Transit Circle telescope at Greenwich.

For some purposes this is still true but certainly not
for all purposes.  Even the much-acclaimed British
Ordnance Survey Maps use a different Longitude 0 (for
the simple reason that the Ordnance Survey started
long before 1884 and they haven't wanted to change!).

The WGS84 model was established by the U.S. who used
a secondary longitude (probably one in Washington) as
a reference during the refining of the model.  When
they finished, it turned out that 0 degrees on the
WGS84 model is about 6 arc-seconds to the EAST of
the longitude of the Airy Transit Circle.

I am writing all this from memory so someone else may
correct this figure of 6 arc-seconds.

If my memory is right this translates into about
0.4 seconds of time or (very roughly) 100 metres
at the latitude of Greenwich.

I don't think diallists should worry too much about
this error.  UTC is allowed to differ from UT1 by over
twice this amount and I expect most diallists use UTC
for checking sundials without correcting to UT1.  [A
few serious pedants like me make this correction!]

To those readers who are familiar with the difference
between UT1 and UTC I should like to have it confirmed
that UT1 STILL uses the Airy Transit Circle as defining
reference longitude 0 degrees.

In short: is it still the case that 12h UT1 is the
instant of superior transit of the mean sun at Airy's
Transit Circle?  I am fairly sure the answer is yes but
I would be happier if some expert could confirm this.

Frank King
Cambridge, U.K.

-



===
 Richard B. LangleyE-mail: [EMAIL PROTECTED]
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142
 University of New Brunswick   Fax:  +1 506 453-4943
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
===
-

Re: Duplicate messages

[Richard Langley]

I have received some duplicates, too.
-- Richard Langley

On Thu, 14 Apr 2005, Mac Oglesby wrote:


For the past several days each message from the sundial list, and
only from the sundial list, has been closely followed by a duplicate
message, but one which concludes with the announcement that this
e-mail has been scanned for viruses by Star. The service is powered
by MessageLabs.

Have others on this list also received duplicate emails, or am I the
only one so blessed?

Mac Oglesby
-



===
 Richard B. LangleyE-mail: [EMAIL PROTECTED]
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142
 University of New Brunswick   Fax:  +1 506 453-4943
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
===

Re: On the greatest size of an analemmatic and more

[Richard Langley]

On Mon, 11 Apr 2005, tony moss wrote:

Frank King Wrote,

Can some U.S. reader who knows all about cold
winters kindly let this temperate Brit know what is
likely to be found underneath this dial?  Is there
really 1200mm of hard-core and elaborate drainage?

The pedestal of the Longyearbyen dial at 87° north is supported what seems to 
be the usual way for such frost-beset areas viz. on wooden piles driven 5 
metres into the ground.
  ^^
  78??

Tony Moss.

-



===
 Richard B. LangleyE-mail: [EMAIL PROTECTED]
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142
 University of New Brunswick   Fax:  +1 506 453-4943
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
===

-

RE: Software Search - Apple Mac!

[Richard Langley]

I have a copy of Sundials (icon has a Martini glass and something beside it
and LUFKIN underneath) -- so I presume this is the right program. It is
version 1.0, copyright 1995 Martiniware. I presume it used to work at one
time. I just tried to execute it under Mac OS 9 and it crashes with an error
report.
-- Richard Langley

On Fri, 11 Feb 2005, Lufkin, Brad wrote:

Many moons ago, I wrote a Mac Sundial program, but I lost my machine and so 
the program is no longer directly available from me. However, it used to live 
on a website (http://dialist.webjump.com) maintained by a contributor to this 
mailing list. The website no longer seems to exist. If the owner of the 
website is reading this, perhaps s/he could forward the program to you.
Regards, Brad
P.S. The program was written in True Basic, so I was able to port it to 
Windows with no trouble. The Windows version is still available from me. One 
of these days, I plan to re-write it in Java, which should make it available 
on all machines with a Java runtime (and that's a lot of machines).

-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] Behalf Of Barry Wainwright
Sent: Friday, February 11, 2005 4:30 AM
To: sundial@rrz.uni-koeln.de
Subject: Software Search - Apple Mac!


Can anyone point me in the direction of good Macintosh software for the
design of sundials? I have seen several windows programmes out there, but
none for Apple Mac.

If there isn't anything already available and there is a reasonable demand,
I may consider writing my own...

--
Barry



-

-



===
 Richard B. LangleyE-mail: [EMAIL PROTECTED]
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142
 University of New Brunswick   Fax:  +1 506 453-4943
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
===
-

Re: Brad Lufkin's Mac software SUNDIALS

[Richard Langley]

Works on an iMac under OS 9.1 but I had to discard the downloaded Preferences
file before it would work correctly. This is a later version of the program
than the one I reported on earlier which apparently doesn't work under more
recent versions of the classic Mac operating system.
-- Richard Langley

On Fri, 11 Feb 2005, Mac Oglesby wrote:


Hello,

I've posted the contents of the Macintosh folder I found for Brad
Lufkin's SUNDIALS at:

http://www.sover.net/~oglesby/Lufkin%20SUNDIALS/

It's not clear to me if all four of the files are absolutely
necessary, but certainly SUNDIALS and Help are.

I don't know very much about the program, so any questions about it
ought to be addressed to Brad. Earlier today I ran SUNDIALS on an
iMac (OS 8.6) and an eMac (OS 9.2.2 Classic mode on a Mac running OS
10.2.8) without any problems.

Cheers,

Mac






-



===
 Richard B. LangleyE-mail: [EMAIL PROTECTED]
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142
 University of New Brunswick   Fax:  +1 506 453-4943
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
===

Re: Sundial at Fredericton.

[Richard Langley]

Mike:
Sorry for taking so long to get back to you and the group about the
Fredericton Soldiers' Barracks sundial. I don't know if the Soldiers' Barracks
sundial made it into Mrs. Gatty's book or not (I have ordered the book through
inter-library loan but it has not arrived yet) but Mrs. Gatty was made aware
of the sundial by her daughter, Juliana, in a letter dated 5 October 1867. She
said ... I have found another dial ­ but it has no motto. It is in the
Barrack Square. But there do seem to be dials in this part of the world,
which is a great point ­  I keep an eye open as you know. And she included
a sketch of the dial http://gauss.gge.unb.ca/sundials/sundial.ewing.jpg.
The letter is reproduced in Canada Home: Juliana Horatia Ewing's Fredericton
Letters 1867-1869, edited by Margaret Howard Blom and Thomas E. Blom, and
published by the University of British Columbia Press, 1983.

Also, for those interested, I've made a scan of the brochure that was prepared
when the sundial was reconstructed:
http://gauss.gge.unb.ca/sundials/SundialBrochure.pdf. In the photo, which
dates from around the turn of the century (the one before the last), the
sundial is barely visible behind the tree. The brochure inclcudes the table
of corrections for EoT, longitude, and daylight saving time.

-- Richard

On Fri, 9 Jul 2004, Mike Cowham wrote:

Dear Richard,
In your reply to John Carmichael about EoT + Longitude Correction Table
you mentioned a sundial at the Fredericton Soldiers Barracks.  This
immediately started bells ringing in my brain because this is the place where
Alexander Ewing and his wife Juliana were stationed in 1867-9.  If you don't
know the connection, then I should tell you that Juliana Ewing was Mrs
Gatty's second daughter - Mrs Margaret Gatty, who wrote the famous Book of
Sun-Dials.
There HAS to be a connection with the Gattys.  Perhaps you know the
story?  I think that the origins of the sundial are really worth following
up.

Regards,
Mike Cowham.
  - Original Message -
  From: Richard Langley
  To: John Carmichael
  Cc: Sundial List
  Sent: Thursday, July 08, 2004 6:04 PM
  Subject: Re: EOT + Longitude Correction Table


  I combined all of the corrections for the table I prepared when helping with
  the faithful reconstruction of the Fredericton Soldiers Barracks sundial over
  a decade ago http://new-brunswick.net/new-brunswick/fredericton/page1.html.
  You can barely see the interpretive plaque low down on the wall. Some day I
  must put some better pictures of the sundial and plaque up on the Web.
  -- Richard Langley




===
 Richard B. LangleyE-mail: [EMAIL PROTECTED]
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142
 University of New Brunswick   Fax:  +1 506 453-4943
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
===

-

Re: EOT + Longitude Correction Table

[Richard Langley]

I combined all of the corrections for the table I prepared when helping with
the faithful reconstruction of the Fredericton Soldiers Barracks sundial over
a decade ago http://new-brunswick.net/new-brunswick/fredericton/page1.html.
You can barely see the interpretive plaque low down on the wall. Some day I
must put some better pictures of the sundial and plaque up on the Web.
-- Richard Langley

On Thu, 8 Jul 2004, John Carmichael wrote:

Hello All,

Some of you wrote me and seemed very confused with my inquiry about a way to
get a EOT table that is longitude corrected.  You ot understand what I
wanted.  So I'll try to explain it here. (thanks to everybody who sent me
info on this)

Sample letter:
I still cannot figure out your EoT problem; EoT does not depend on
longitude, it depends on an agreed absolute (GMT) and changes so little in
any time zone you cannot see the difference on a dial.  Maybe I am missing
something, I often do these days.

Yes, you are missing something.  And it's so simple you will kick yourself.
You're thinking too deeply!  I'll try to explain...

Of course you are correct in implying that EOT values are Universal and
are basically the same all over the world, at any longitude or latitude and
on any given date. You can use the same EOT graph with almost any sundial
anywhere in the world. But you know that already.  So far so good.

But if somebody really wants to know clock time, then not only does he
have to correct his sundial readings for EOT, but he also has to correct for
his longitude (and Daylight Saving Time if applicable).  This additional
longitude correction is expressed as a plus or minus value in minutes and
seconds.  But you know this already.  So far so good.

Now this double correction is sometimes confusing to non-dialists (it's a
triple correction if one has to correct for Daylight Savings too).  So to
reduce two time reading corrections into just one correction, you can add
the EOT correction to the longitude correction since both expressed in
minutes and seconds, and you come up with a new EOT graph or table that
incorporates the longitude time correction in its values.

Now do you get it?  Neat huh!

For my sundial customers, I usually build the longitude correction directly
into my sundial faces so the customer doesn't have to do the longitude
correction, just the EOT correction.  This combined EOT+Longitude Correction
Table is very useful if you have an antique pre-timezone sundial or any
sundial that doesn't have a built-in longitude correction.  The downside is
that you have to make a unique customized EOT table for each sundial,
depending on its particular longitude.

Hope this helps

===
 Richard B. LangleyE-mail: [EMAIL PROTECTED]
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142
 University of New Brunswick   Fax:  +1 506 453-4943
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
===
-

Re: Roman Numerals - as a test message

[Richard Langley]

Tony:
Isn't  the clockmaker's IV? Apparently introduced since it balances
VIII although that's not a theory that is without problems since other
numbers on the clock face are not balanced. While not necessarily
authoratative, see
http://www.wilkiecollins.demon.co.uk/roman/clockface.htm.
-- Richard

On Sat, 27 Mar 2004, tony moss wrote:

Fellow Shadow Watchers,
   I've just noticed that the BBC TV News credit
titles include the date as MMIV.  Should this be MM?  I recall being
'smacked' by a BSS lady member for using a 'clock makers' IV' in my early
attempt at Roman numerals some years ago.

Tony Moss
-



===
 Richard B. LangleyE-mail: [EMAIL PROTECTED]
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142
 University of New Brunswick   Fax:  +1 506 453-4943
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
===
-

Re: Roman Numerals - as a test message

[Richard Langley]

According to
http://www2.inetdirect.net/~charta/Roman_numerals.html#footnote4, the Romans
themselves rarely used the subtraction principle and so would have primarily
used  rather than IV.
-- Richard

On Sat, 27 Mar 2004, tony moss wrote:

Richard Langley wrote:

Isn't  the clockmaker's IV? Apparently introduced since it balances
VIII although that's not a theory that is without problems since other
numbers on the clock face are not balanced. While not necessarily
authoratative, see
http://www.wilkiecollins.demon.co.uk/roman/clockface.htm.

Thanks Richard.  An interesting website which gives the opposite message
to the one which was suggested to me.

I suppose my question should have been - What form was actually used by
the Romans in their own time?

Tony M.
-



===
 Richard B. LangleyE-mail: [EMAIL PROTECTED]
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142
 University of New Brunswick   Fax:  +1 506 453-4943
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
===
-

Re: Magnetic variation.

[Richard Langley]

The DoD World Magnetic Model predicts for 1 March 2004 at the given location a
magnetic declination of 4.06 degrees (compass will theoretically point
4.06 degrees to the east of true north). A different magnetic model,
the International Geomganetic Reference Field, gives 4.22 degrees. Take
your pick. Local iron deposits, geomagnetic activity, etc. could have an
effect on the compass reading. Incidentally, the WMM magnetic dip is 82.11
degrees -- the magnetic field lines are almost vertical. For this reason, the
horizontal field strength (to which the compass is sensitive) is not as strong
as that at more southerly locations. Any further north (or, more precisely,
towards the north magnetic pole) and a compass starts to become erratic.
More info here http://www.ngdc.noaa.gov/seg/potfld/faqgeom.shtml.
Have fun.
-- Richard Langley
   Professor of Geodesy and Precision Navigation

On Sat, 28 Feb 2004, tony moss wrote:

Fellow Shadow Watchers,

   Next week I will be setting off for Longyearbyen on
Spitsbergen in the Svalbard group of islands 500 miles north of Tromso to
install their new 24 hour stainless steel sundial.  As any diallist is
painfully aware the most probable event for dial installation is an obscured
sun all day so for the purposes of the inauguration ceremony and photoshoot
we may be forced to do the diallistically unspeakable viz. a temporary
magnetic alignment so that at least it looks OK -ish.

Having consulted various geomagnetic websites for that area, like Omar
Khayyam, I Came out by the same Door as in I went because the magnetic map
at 78° 12' North 15° 40' is exceedingly complex.

Can anyone tell me the likely current magnetic variation at those coordinates 
please?

Thanks in anticipation.

Tony Moss

P.S.  I bought my snow boots yesterday and overnight we had a full six inches 
of white stuff in which to try them out so I hope the same Good Luck continues.

-



===
 Richard B. LangleyE-mail: [EMAIL PROTECTED]
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142
 University of New Brunswick   Fax:  +1 506 453-4943
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
===

-

Re: Salvador Dal� and Sundials

[Richard Langley]

Thanks, Frans. It looks like Dalí's Paris dial was based on this one in
Cadaqués, predating it by 2 years. I wonder if there are any other Dalí dials
of the same style? And thanks for pointing out the Dalí anagram -- I had
missed that.
By the way, the small fishing village of Portlligat (the site of the Dalí
paianting) is just next door to Cadaqués.
-- Richard
P.S. Sorry for the earlier typo on the Fredericton Dalí painting; of course it
should have been Santiago El Grande.
   ^

On Tue, 3 Feb 2004, Frans W. Maes wrote:

Hi Richard  all,

There is a picture of a Dali dial (:-) in the site of Andreas Hänel from
Osnabrück (in German):
http://www.physik.uni-osnabrueck.de/~ahaenel/sonnuhr/
Scroll to Spanien/Katalonien - Cadaques.

It is dated 1966. Judging from the hour line pattern, the dial is
east-declining by 60° or so. The pole-style possibly suffered from some
'restoration'.

The site does not give additional information. Note the disclaimer that some
attributions may be incorrect.

Cadaqués is a village on the east coast of Spain, close to the French border
and close to Dali's native town Figueras.

Regards,
Frans Maes
53.1N 6.5E

- Original Message -
From: Richard Langley [EMAIL PROTECTED]
To: sundial@rrz.uni-koeln.de
Sent: Monday, February 02, 2004 3:08 PM
Subject: Salvador Dalí and Sundials


While on a recent holiday in southern Florida, my wife and I visited the
Salvador Dalí Museum in St. Petersburg http://www.salvadordalimuseum.org/.
Currently running is the exhibition Dalí Centennial: An American
Collection
which celebrates the 100th anniversary of the birth of Dalí. One of the
paintings on display is Noon (Barracks Port Lligat) which Dalí
painted in 1954 http://dali.karelia.ru/html/works/1954_07.htm. The
painting
shows a vertical sundial on the wall of the barracks. Can any of our Spanish
colleagues tell us if the building and the sundial still exist?

Of course, Dalí was no stranger to sundials as witnessed by his famous
sundial
at 27, rue Saint-Jacques, Paris 5ème arrondissement
http://www2.iap.fr/saf/csmp/arr5n/centrea51.html constructed in 1968.

The image on the sundial bears a bit of a resemblance to his 1966 painting
Self Portrait Sundial
http://www.elainefineart.com/dali/self_portrait_sundial.htm

Are there any other Dalí sundials -- real or painted?

-- Richard Langley

P.S. Fredericton is home to Dalí's huge Satiago El Grande. It is on
permanent display in the city's Beaverbrook Art Gallery
http://www.beaverbrookartgallery.org/, one of 4 Dalí paitings it owns. The
gallery was a gift to New Brusnwick from its native son Lord Beaverbrook
(Sir
Max Aitken) who served in the wartime cabinet of Winston Churchill. Lord
Beaverbrook was chancellor of my university from 1947 until his death in
1964.


===
 Richard B. LangleyE-mail: [EMAIL PROTECTED]
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142
 University of New Brunswick   Fax:  +1 506 453-4943
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/

===

-

-



===
 Richard B. LangleyE-mail: [EMAIL PROTECTED]
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142
 University of New Brunswick   Fax:  +1 506 453-4943
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
===

-

Re: Oblate Spheroid correction for computing distances?

[Richard Langley]

WGS 84 ellipsoid semi-major (equatorial) axis: 6 378 137.0 m
 semi-minor (polar) axis:  6 356 752.3142 m
(biaxial ellipsoid or just ellipsoid is the preferred (at least in North
America) term for spheroid)

What kind of differences might you see when comparing great circle routes on
an approximating sphere with geodesics on the ellipsoid? As an example, the
distance between Washington and L.A. on the sphere is approximately 3711 km.
On the ellipsoid, it is 3719 km.

Here are the expressions for computing the distance in km for one degree of
latitude or longitude on the WGS 84 ellipsoid as a function of latitude, phi:
lat = 111.13295 - 0.55982Cos 2 phi + 0.00117Cos 4 phi
long = 111.41288 Cos phi - 0.09350 Cos 3 phi + 0.00012 Cos 5 phi

See Navigation 101: Basic Navigation with a GPS Receiver
http://gauss.gge.unb.ca/papers.pdf/gpsworld.october00.pdf for further
details.

Navigate is a handy application for computing geodesics on various
ellipsoids for PDAs using the Palm OS:
http://fermi.jhuapl.edu/navigate/index.html

-- Richard Langley
   Professor of Geodesy and Precision Navigation

On Tue, 3 Feb 2004, Thaddeus Weakley wrote:

Hello All -

Tony's posting reminds me of a question that I have had for a long time.  As 
many of us know, we call geometrically compute the distance between two 
locations (lat, long) and (lat2, long2) assuming that the Earth is a perfect 
sphere (which of course it isn't).  Has anyone seen a correction for this 
flattening at the poles, or bowing around the equator?  If so, please share.

Thanks,

Thad Weakley
42.2N,  83.8W




-
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Yahoo! SiteBuilder - Free web site building tool. Try it!


===
 Richard B. LangleyE-mail: [EMAIL PROTECTED]
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142
 University of New Brunswick   Fax:  +1 506 453-4943
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
===
-

Salvador Dal� and Sundials

[Richard Langley]

While on a recent holiday in southern Florida, my wife and I visited the
Salvador Dalí Museum in St. Petersburg http://www.salvadordalimuseum.org/.
Currently running is the exhibition Dalí Centennial: An American Collection
which celebrates the 100th anniversary of the birth of Dalí. One of the
paintings on display is Noon (Barracks Port Lligat) which Dalí
painted in 1954 http://dali.karelia.ru/html/works/1954_07.htm. The painting
shows a vertical sundial on the wall of the barracks. Can any of our Spanish
colleagues tell us if the building and the sundial still exist?

Of course, Dalí was no stranger to sundials as witnessed by his famous sundial
at 27, rue Saint-Jacques, Paris 5ème arrondissement
http://www2.iap.fr/saf/csmp/arr5n/centrea51.html constructed in 1968.

The image on the sundial bears a bit of a resemblance to his 1966 painting
Self Portrait Sundial
http://www.elainefineart.com/dali/self_portrait_sundial.htm

Are there any other Dalí sundials -- real or painted?

-- Richard Langley

P.S. Fredericton is home to Dalí's huge Satiago El Grande. It is on
permanent display in the city's Beaverbrook Art Gallery
http://www.beaverbrookartgallery.org/, one of 4 Dalí paitings it owns. The
gallery was a gift to New Brusnwick from its native son Lord Beaverbrook (Sir
Max Aitken) who served in the wartime cabinet of Winston Churchill. Lord
Beaverbrook was chancellor of my university from 1947 until his death in 1964.

===
 Richard B. LangleyE-mail: [EMAIL PROTECTED]
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142
 University of New Brunswick   Fax:  +1 506 453-4943
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
===

-

Re: Sundials and atomic clocks

[Richard Langley]

And, there is a long, popular level article on leap seconds and GPS
(prompted by the recent Motorola GPS receiver problem) in the 22 November
issue of New Scientist now on newsstands.
See also the article GPS and Leap Seconds: Time to Change? which appeared in
my Innovation column in GPS World in the November 1999 issue. A PDF file of
the article may be found here:
http://iraf.noao.edu/~seaman/leap/GPS-Nov99_Innov.pdf.
-- Richard Langley
   Professor of Geodesy and Precision Navigation
   and Contributing Editor, GPS World Magazine

On Mon, 1 Dec 2003, Woody Sullivan wrote:

This article will be of interest to those of you interested in those
weird leap seconds that sometimes get added to our clocks on New
Year's Eve due to the unpredictable changes in the Earth's rotation.
Ironically, amidst discussions of keeping time with the finest atomic
clocks, one factor in the debate is whether or not anyone cares about
(equally accurate) local solar time, as measured directly by a
sundial.



Leap Second Debate Heats Up  [from Physics Today, Oct. 2003, p. 34]

Keep leap seconds, and glitches in telecommunications, navigation by
satellite, and legal marking of time could become more frequent and
serious. Lose them, and astronomers will have trouble pointing their
telescopes, and eventually the time of day will get out of sync with
Earth's rotation.

At the crux of a debate about whether to continue inserting leap
seconds into Coordinated Universal Time (UTC), the standard in many
countries, is the unpredictability of Earth's rotation. Millennia-old
eclipse data show that Earth has long been slowing down. Nowadays,
Earth's rotation is measured by observing quasars with very long
baseline radio interferometry. The deceleration is chiefly due to the
tidal pull of the Moon; fluctuations on shorter time scales come
from, among other things, the oceans and atmosphere and core-mantle
interactions.



A leap second every year or two has been the norm, though none has
been added since 1999, and timekeepers predict that more leap seconds
will be needed in the future. Without leap seconds, official time
will diverge from solar time by an estimated two minutes by the end
of this century; in 3000 years, the drift might be about eight hours.

This month, a special rapporteur group (SRG) will submit its
recommendations on the leap second to the International
Telecommunication Union, where the matter will wend its way through
various committees before a final decision is reached--a process that
could take years. Says SRG chair Ron Beard, a physicist at the US
Naval Research Laboratory, The issue is: Is relating to the solar
day of significance? And how does that weigh against the problems
that come with introducing integral seconds?

Sundials are the only clocks that mark time directly from Earth's rotation.
Before 1972, clocks were corrected with fractions of seconds and by
adjusting the length of the second. Since then, leap seconds have
been added to keep UTC within nine-tenths of a second of solar time
and synchronized with international atomic time, but with an
offset--currently 32 seconds. The atomic second is based on the
frequency of a hyperfine transition in cesium.

But with technology relying increasingly on the precision of atomic
time, the leap second has come under scrutiny. Abolishing it would
have political, economic, legal, religious, and safety implications.
Says SRG secretary William Klepczynski, an astronomer and timekeeping
consultant, There are all sorts of little technical problems that
you can see start to raise their heads in our society. Before they
become big problems, we should have one time for everybody. For
example, he says, bank recordings of interaction times run into
trouble when computers can't distinctly label a leap second. When
leap seconds were inserted in 1994 and 1997, he adds, the Russian
global positioning system, GLONASS, went off the air for several
hours. Mistakes in timekeeping could lead to flight accidents, says
Felicitas Arias, who heads the time section of the Bureau
International des Poids et Mesures near Paris. Leap seconds are a
nuisance, and they could be a danger, she adds.

The SRG hasn't reached consensus, says Dennis McCarthy, director of
time at the US Naval Observatory in Washington, DC. But we came up
with a draft recommendation that asks for the leap second to go away,
arbitrarily in 2022--fifty years after its introduction. That should
give astronomers and others time to cope with software glitches, he
says.

But some astronomers worry that leap seconds will be dropped sooner
and without adequate notice. Some people would like never to insert
another leap second, says Steve Allen, a telescope programmer at the
University of California, Santa Cruz's Lick Observatory. Telescope
pointing systems are one of the first things that would break. It's
like a Y2K analysis, he says. You have to go through and figure

Re: BBC radio program(me) on sundials on 13 Dec.

[Richard Langley]

The Radio 4 longwave transmitter is on 198 kHz. Not 198 m mediumwave.
Reception is more or less restricted to Europe.
-- Richard Langley
   Professor of Geodesy and Precision Navigation

On Fri, 28 Nov 2003 [EMAIL PROTECTED] wrote:


In a message dated 2003/11/27 02:50:54 PM, [EMAIL PROTECTED] writes:

 BBC Radio 4  will carry a 30-minute show on sundials on Saturday, 13
 December at 1530 GMT.

 It's of course easy to hear in the UK, but anyone with a Web
 connection who can stream audio can also listen at

 http://www.bbc.co.uk/radio4/

 or through the ether on long wave at 198 meters.

I have a shortwave receiver that picks up BBC on 5975 kHz rather
well.  Will the program be at that frequency also?  (This ancient
computer won't handle streaming audio.)

What would the frequency of 198 m be?  Is that a band, rather
than a frequency?  Haven't heard of that band, but I'm a rank novice
at this sort of thing.  Let's see... 299792458/198 = 1514 kHz  (Not
correcting for the refractive index of air.)  Have I messed that up?

Thanks!
John Bercovitz

-



===
 Richard B. LangleyE-mail: [EMAIL PROTECTED]
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142
 University of New Brunswick   Fax:  +1 506 453-4943
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
===
-

Re: Sundials in Paris

[Richard Langley]

The article is available on line at
http://www.nytimes.com/2003/03/16/travel/16bpsun.html.
Concerning the Salvador Dali dial, as I recall, it's not mounted correctly.
It's not on the correct facing wall.
-- Richard Langley

On Sun, 16 Mar 2003 [EMAIL PROTECTED] wrote:

3-16-03

Please note the article on page 17 in this Sunday's New York Times Travel
Section entitled Solar-Powered Timekeeping in Paris.  The author's
reference for her sundial search was Cadrans Solaires de Paris by Andre
Gotteland and Georges Camus.

Fred Sawyer - perhaps you could send some information to the author and her
husband on the benefits of NASS membership?

Hal Brandmaier



===
 Richard B. LangleyE-mail: [EMAIL PROTECTED]
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142
 University of New Brunswick   Fax:  +1 506 453-4943
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
===

-

Re: OS Map refs.

[Richard Langley]

The use of grid squares for the U.K. National Grid was introduced to reduce
the number of digits required to give a reference. E.g., for a place with full
National Grid coordinates 538857.2345 metres easting, and 177345.3456
metres northing (a position given to the nearest 0.1 millimetres -- pushing
the limits of even GPS technology), the grid square designation to the
nearest metre is TQ 3885777345. Grid squares are  really only helpful for low
precision references. See http://www.gps.gov.uk/natgrid/introduction.asp for
further explanation.
-- Richard Langley
   Professor of Geodesy and Precision Navigation

On Tue, 10 Sep 2002, Ian Maddocks wrote:

Hi Tony

Am I correct in thinking that:
OSX the 'Grid East Value' and
OSY the 'Grid North Value?   in this context?  O-)

Yes - if you look on the OSGB map included in the BSS glassary
http://www.sundialsoc.org.uk/glossary/ap11/ap11.htm
the 0-700km eastings and 0-1300km northings are noted up the sides.

I first found this form of grid reference used last year - at the end of the 
Foot  Mouth crisis i downloaded a table of footpaths in the lake district 
that were open , given as 12 figure references!
for example those in NX grid square were 3EEEee5NNNnn.  ie what would 
normally be NX EEENNN.   Yes with enough digits they were quoted to the 
nearest meter!

regards

Ian Maddocks




_
Join the world?s largest e-mail service with MSN Hotmail. 
http://www.hotmail.com

-



=== 
 Richard B. LangleyE-mail: [EMAIL PROTECTED]  
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142  
 University of New Brunswick   Fax:  +1 506 453-4943  
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
=== 



-

Re: Quotation?

[Richard Langley]

On Thu, 25 Jul 2002, Patrick Powers wrote:

Message text written by INTERNET:sundial@rrz.uni-koeln.de

Amyddst ye flowres I tell ye houres
Tyme wanes awaye as flowres decaye
Beyond ye tombe fresh flowers bloome
Soe man shall ryse aboe ye skyes

Back yet again!  This has got me hooked!!   I have also found reference to
this rhyme in 'Sundials and Roses of Yesterday'  by Alice M Earle 1902, p
271-3.

She confirms that the motto was written by Rev Greville J Chester and it
appears in his novel Aurelia as part of his description of the Bishop's
(that's Bishop Redryngton's) garden  Apparently this novel's description
was so 'real' that others copied the motto thereafter.  It was for example
engraved on the lower steps of a faceted dial at Linburn, Midlothian which
was designed by Thomas Ross.

Presumably we would need to establish the date of the novel 'Aurelia' in
order to get to the date of the motto.  I don't have any knowledge of that
though.

From The British Library Public Catalogue:

Title:  Aurelia, or, the Close at Mixeter. Sketches in a cathedral city. 

Main heading:   CHESTER. Greville John 

Publication details:pp. 272. M. Ward  Co.: London, 1882. 8o. 

Shelfmark:  12643.f.14. 

-- Richard Langley
   Professor of Geodesy and Precision Navigation

=== 
 Richard B. LangleyE-mail: [EMAIL PROTECTED]  
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142  
 University of New Brunswick   Fax:  +1 506 453-4943  
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
=== 

-

Re: Mosaic-2

[Richard Langley]

There is a largish picture of the mosaic on the Web:
here: http://www-gap.dcs.st-and.ac.uk/~history/PictDisplay/Plato.html.
-- Richard Langley

On Thu, 11 Jul 2002, Gianni Ferrari wrote:

 Some notes
The mosaic, called  also Plato's Academy,   is , at present,   in the 
National Archaeological Museum in Naples  (Museo Archeologico Nazionale di 
Napoli) .

A second copy, made around one century after, was   discovered in Sarsina 
(Italy) in the XVIII century and it is nowin the Villa Albani,  in Rome.  

The original   has gone lost.  

Gianni Ferrari

44? 39' N  10? 55' E
Mailto : [EMAIL PROTECTED]

=== 
 Richard B. LangleyE-mail: [EMAIL PROTECTED]  
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142  
 University of New Brunswick   Fax:  +1 506 453-4943  
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
=== 


-

RE: Astrolabe on coin

[Richard Langley]

See also:
http://www.cnb.cz/en/_platidla/ceske_mince/20_koruny2000.htm
-- Richard Langley

On Wed, 18 Apr 2001, Martha A. Villegas wrote:

On the James E. Morrison site about astrolabes, there is a very nice picture
of this coin

http://www.astrolabes.org/links.htm

Martha A. Villegas

-Mensaje original-
De: Thibaud Taudin-Chabot [EMAIL PROTECTED]
Para: sundial@rrz.uni-koeln.de sundial@rrz.uni-koeln.de
Fecha: Martes, 17 de Abril de 2001 01:07 p.m.
Asunto: Astrolabe on coin


On the Chech coin of 20 Crowns is a picture of an astrolabe.
Is this a copy of an existing one or is it a design made only for the coin?

Thibaud Chabot

-
Thibaud Taudin-Chabot
52?18'19.85 North  04?51'09.45 East
home email: [EMAIL PROTECTED]
(attachments max. 500kB; for larger attachments contact me first)




=== 
 Richard B. LangleyE-mail: [EMAIL PROTECTED]  
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142  
 University of New Brunswick   Fax:  +1 506 453-4943  
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
=== 

Re: Time Zones

[Richard Langley]

The time zone boundaries in North America are quite irregular. Have a look at
http://www.nrc.ca/inms/time/tze.html for the current Canadian time zone
maps.
-- Richard Langley
   Professor of Geodesy and Precision Navigation

On Tue, 27 Mar 2001, harriet wrote:

Dear All,

Can anyone clarify American and European time zones for me? I am trying
to write instructions for setting up a dial which can be used in any
location.

The NASS dialist's companion gives the meridians for US time zones
as: Atlantic 60? W
   Eastern  75? W
   Central  90?W
   Mountain 105? W
   Pacific 120?W

Do all Americans adhere to these time zones, or are some like the French
who
like to be one hour ahead of GMT even though France lies within 7.5? of the
Greenwich
Meridian?

If I set up a dial in say Pittsburg, Pennsylvania (longitude 80? W) which
tells local solar time,
ignoring corrections for the Equation of Time, am I correct in saying that
it will run 20 minutes slow to Eastern Standard Time as it is 5? west of
the Eastern time meridian?

Do countries in Europe apart from France adhere to the 'correct' zone? 
What about daylight saving in the US and Europe?

Any help gratefully received.

Harriet James  



=== 
 Richard B. LangleyE-mail: [EMAIL PROTECTED]  
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142  
 University of New Brunswick   Fax:  +1 506 453-4943  
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
=== 

Re: sunspots

[Richard Langley]

According to a NASA Web site:

The MDI (Michelson Doppler Imager) images shown here are taken in the
continuum near the NiI 6768 Angstroms line. The most prominent solar
features are the sunspots on the solar photosphere. This is very much
how the Sun looks like in the visible range of the spectrum (for example,
looking at it using special 'eclipse' glasses: Remember, do not ever
look directly at the Sun!). 

-- Richard Langley

On Wed, 3 Jan 2001, Gordon Uber wrote:

John,

I think that the SOHO images are updated at least once a day. The latest 
sunspot image was taken at 10:16 UT today. The satellite is in a 
zero-gravity region between the earth and the sun, so I would think that it 
is always on our side of the sun, although I don't know for certain. The 
sun's rotation period is a function of latitude, 25 days at the equator, 33 
days at 75 degrees (Skilling and Richardson, 1947).

SOHO images are at
http://sohowww.nascom.nasa.gov/data/realtime-update.html

Gordon


At 07:14 AM 1/3/01 -0700, you wrote:
 Hello all:

I just looked at the SOHO solar satellite photos of the sunspots and noticed
that the spots were different from the ones I saw on Christmas morning.
Could it be that SOHO was on the opposite side of the sun when the picture
was taken? Or maybe the sun's rotation since Christmass brought the sun's
farside into view.

If an earthboud observer wants to see both sides of the sun, how long will
he have to wait between observations until the sun rotates 180 degrees?
What is the rotation rate of the sun?

John Carmichael
Tucson Arizona

Gordon Uber   [EMAIL PROTECTED]  San Diego, California  USA
Webmaster: Clocks and Time: http://www.ubr.com/clocks




=== 
 Richard B. LangleyE-mail: [EMAIL PROTECTED]  
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142  
 University of New Brunswick   Fax:  +1 506 453-4943  
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
=== 

Sundial Article in Weatherwise Magazine

[Richard Langley]

The July/August 2000 issue of Weatherwise, a popular-level magazine about the
weather available on North American magazine racks, features an article on
sundials (Time is But a Shadow).  Includes photos of 12 sundials and
mentions the NASS and BSS Web sites.

=== 
 Richard B. LangleyE-mail: [EMAIL PROTECTED]  
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142  
 University of New Brunswick   Fax:  +1 506 453-4943  
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
=== 

Re: GPS Accuracy

[Richard Langley]

You have been given the wrong information.  Before SA was turned off, the
official accuracy was 100 metres (95%) but with 27-28 satellites, typically
accuracy under good conditions was 50-60 metres (95%).  Turning off SA
improved accuracy from 5 to 10 times, so at most to just under 10 metres
(95%) -- but not to 1 metre.  For such accuracies you still need differential
GPS. Most receivers can be programmed to display coordinates in decimal
degrees, degrees and minutes, or degrees, minutes, and seconds.  Grid
coordinates  (northings and eastings are also possible).  There's a wealth of
GPS info on the Web if you need further info.
-- Richard Langley

On Sat, 13 May 2000, Allan Pratt wrote:

As most of you know, the US government has relaxed the restrictions on
the GPS system. Supposedly the accuracy has improved from 10 meters to 1
meter. My question is, do the actual GPS units in use permit this
accuracy? At the equator, one degree is 111,308 meters in length.
One-meter is thus .09 (9 millionths) of a degree. Even as far north
as Miami FL, a meter is about .1 (1 one-hundred-thousanths) of a
degree. At my location, a meter is .107 degrees. Do the GPS units
read out to 5 or 6 decimal digits of accuracy?

Al Pratt
33 20 36 N
111 54 14



=== 
 Richard B. LangleyE-mail: [EMAIL PROTECTED]  
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142  
 University of New Brunswick   Fax:  +1 506 453-4943  
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
=== 

Re: Marathon, GPS and sundials

[Richard Langley]

Yes, it is confirmed.  See 
http://www.cnn.com/2000/TECH/computing/05/02/civil.gps.idg/index.html
and
http://www.spacecom.af.mil/usspacecom/gps_support/.
-- Richard Langley
   Professor of Geodesy and Precision Navigation

On Tue, 9 May 2000, Fernando Cabral wrote:

Dear fellows in sundialling

Here I am, back from Morroco after surviving the Sahara
Desert and the most gruelling foot race available for
mad people like myself (http://www.sandmarathon.com, http://www.aoicimbaly.com)

The first thing I read after sitting in my desk was that
the American government has relinquished the controlled availabity
for the GPS system. Nevertheless, the source was not reliable
and does not hint to the original source.

Is this a confirmed news?

Best regards

- fernando


--
Fernando Cabral Padrao iX Sistemas Abertos
mailto:[EMAIL PROTECTED]  http://www.pix.com.br
Fone Direto: +55 61 329-0206mailto:[EMAIL PROTECTED]
PABX: +55 61 329-0202   Fax: +55 61 326-3082
15? 45' 04.9 S 47? 49' 58.6 W
19? 37' 57.0 S 45? 17' 13.6 W





=== 
 Richard B. LangleyE-mail: [EMAIL PROTECTED]  
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142  
 University of New Brunswick   Fax:  +1 506 453-4943  
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
=== 

Re: A Comment and a Question

[Richard Langley]

On Wed, 12 Apr 2000, Robert Terwilliger wrote:

Hi All,

Comment: I think the problem with rotating or skewing text in graphics
files could be solved if the text character entities could be converted
into the vector lines and curves which make them up. I don't think this
is easy to do with True Type fonts.

Question: Is there a source, or value, for the exact inclination of the
earth's axis? I understand it is decreasing slightly. The last value I
used was 23.4385 degrees. I cannot remember where I got it.

The obliquity of the ecliptic at J2000.0 is 23.4393 degrees (or, to more
precision, 84381.412 arc seconds with an uncertainty of 5 milli-arc seconds).
This is the value associated with the JPL DE403/LE403 planetary and lunar
ephemerides.  There is a variation in the obliquity due to the nutation of the
earth's rotation axis.  And also longer term variations due to the
purturbation of the earth's orbit by the other members of the solar system.

=== 
 Richard B. LangleyE-mail: [EMAIL PROTECTED]  
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142  
 University of New Brunswick   Fax:  +1 506 453-4943  
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
=== 

Arrows of Time

[Richard Langley]

The Royal Institution Christmas Lectures this year are on time.  They are
being broadcast on BBC television and the BBC have put up summaries of the
lectures along with a lot of background information on their Web site.  Even
though primarily intended for a younger audience, the pages are worth a look.
Even an item on sundials.  The main page is
http://www.bbc.co.uk/rilectures/.

=== 
 Richard B. LangleyE-mail: [EMAIL PROTECTED]  
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142  
 University of New Brunswick   Fax:  +1 506 453-4943  
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
=== 

And Another BBC Item: Greenwich Electronic Time!

[Richard Langley]

See 
http://news2.thls.bbc.co.uk/hi/english/sci/tech/newsid_58/580334.stm
for a news item on Greenwich Electronic Time to be launch on New Year's Day.

=== 
 Richard B. LangleyE-mail: [EMAIL PROTECTED]  
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142  
 University of New Brunswick   Fax:  +1 506 453-4943  
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
=== 

Re: Dollars and sense!

[Richard Langley]

I believe there is no commission charge to the recipient of a Pound Sterling
Money Order. The charge to the purchaser is typically a few dollars but
depends on one's bank plan or whether one purchases a money order at the post
office.  Bank drafts typically cost the purchaser a dollar or two more than a
money order.
-- Richard Langley
   Professor of Geodesy and Precision Navigation

On Sat, 4 Dec 1999, Tony Moss wrote:

Fellow Shadow Watchers,
   Just at the moment a fair amount of my brassware 
seems to be heading for the USA and this always presents the problem of 
payment in another currency and the disproportionate amount of commission 
charged by the *licenced robbers* - sorry - 'banks' when handling small 
amounts.

My preferred  solution is for a bank draft in 'Pounds Sterling' and I 
remember being told that there are agencies who can handle this by post 
at reasonable rates.  If anyone can recommend a US agency to handle such 
things, or a better method, I'd be pleased to pass on the good news.

Best Wishes

Tony Moss

P.S.  I've looked at credit card trading but this doesn't work for 
smallish irregular transactions.  It would be ideal otherwise.




=== 
 Richard B. LangleyE-mail: [EMAIL PROTECTED]  
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142  
 University of New Brunswick   Fax:  +1 506 453-4943  
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
=== 

Re: The end (?) of DST... (and UTC leap seconds)

[Richard Langley]

Not that it will affect sundials in the short term, but discussions are 
underway to abolish or modify the procedure of adding leap seconds to UTC
every year or two.  See the November issue of GPS World for details.
-- Richard Langley
   Professor of Geodesy and Precision Navigation

On Wed, 3 Nov 1999, Jeff Adkins wrote:

I think that dialists hate DST because it is an inelegant or clumsy solution 
to
the problem of reconciling fixed clock time to the variable sunrise time in
middle latitudes.

I don't know of a better solution; perhaps the listserv readers have a creatie
suggestion.

On a related point, consider this:

What about going back to simple solar time?  With today's digital technology
clocks could be made retro so as to display sundial time as a function of 
date,
as opposed to making sundials try to display clock time!

Something to think about.

Jeff Adkins

John Carmichael wrote:

 Psyko Kid wrote:

 I know that most dialists hate daylight savings time (for what reason I'm
 still not sure)  Anyway I thought I'd rub salt in your wounds by telling you
 that I am probably the only person on the planet who has decided to stick
 with daylight savings time.  I have a flexible employer, and I enjoy having 
 a
 bit of daylight when I get home for bike riding or whatever.
 (Please send any hate mail to [EMAIL PROTECTED])

 Dear Mr. Kid:

 If your employer is so flexible, then ask him to let you go to work and
 come home one hour earlier, then help us get rid of Daylight Saving Time!

 Happily Standardized in Arizona,

 John Carmichael

--
=-=-=-=-=-=-=-=-=-=-=-=-=
[EMAIL PROTECTED]
Jeff Adkins
Location: 38.00 N, 121.81 W
CA, USA, Earth, Sol III





=== 
 Richard B. LangleyE-mail: [EMAIL PROTECTED]  
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142  
 University of New Brunswick   Fax:  +1 506 453-4943  
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
=== 

Re: GPS

[Richard Langley]

I wrote an in depth article on the roll-over for GPS World.  It's on their Web
site: http://www.gpsworld.com
-- Richard Langley
   Professor of Geodesy and Precision Navigation

On Mon, 16 Aug 1999, Keith E. Brandt, M.D. wrote:

Frank,
Check out http://www.space.com/news/gps_rollover.html for a newspaper-style 
story on the GPS rollover, due to occur 22 Aug 99.

Keith

At 13:11 8/16/99 , you wrote:
My wife half-heard a piece on the radio this morning saying that GPS
instruments would fail next week unless they had previously been
modified to take account of some transmission changes.  They would
simply be unable to find a position.  Sound a bit like the millennium
bug.  Does anyone have any information about this, please?  Users were
advised to contact their suppliers.  I'm feeling lost already so can you
help?

Frank
--
Frank Evans

=
Keith E. Brandt, MD, WD9GET || Goodbye, cruel world that was my home-
  Resident in Aerospace Medicine ||there's cleaner space out here to roam.
San Antonio, TX || Put my feet up on the moons of Mars-
[EMAIL PROTECTED]||sit back, relax, and count the stars.
http://www.dca.net/~brandt  ||
=



=== 
 Richard B. LangleyE-mail: [EMAIL PROTECTED]  
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142  
 University of New Brunswick   Fax:  +1 506 453-4943  
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
=== 

Re: Book by Mueller

[Richard Langley]

Are you thinking of Spherical and Practical Astronomy as Applied to Geodesy by
Ivan Mueller (Ungar, ISBN 0-8044-4667-9)
or
Astronomical Algorithms by Jean Meeus (Willmann-Bell, ISBN 0-943396-35-2)?

-- Richard Langley
   Professor of Geodesy and Precision Navigation

On Wed, 4 Aug 1999, Anton Reynecke wrote:

Good morning!

I need some help with finding a (well-known, I'm sure) book by Mueller.
The title is something like Fundamental astronomical algorithms.

I probably have the title wrong, but it should be recognizable, as it has
been mentioned on this list before, but I can't remember by whom.

I tried a search at Amazom.com, with no luck.

I would appreciate some more info, maybe the ISBN number please!


Regards across the planet
D.Anton Reynecke





=== 
 Richard B. LangleyE-mail: [EMAIL PROTECTED]  
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142  
 University of New Brunswick   Fax:  +1 506 453-4943  
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
=== 

Re: heliograph

[Richard Langley]

On Wed, 23 Jun 1999, Frank Evans wrote:

Maybe somebody can remember more of Kipling's poem referred to earlier
than I can.  Or even the title.  It was about India, I'm fairly sure.
Part went something like:

Are you there, are you there, are you there?
Three sides of a ninety mile square,
With a helio winking like fun in the sun,
Are you there, are you there, are you there?

Here it is.  It's a bit more dialectal than you remember! ;-)


Chant-Pagan
by Rudyard Kipling

ENGLISH IRREGULAR, DISCHARGED


Me that 'ave been what I've been --
  Me that 'ave gone where I've gone --
Me that 'ave seen what I've seen --
  'Ow can I ever take on
With awful old England again,
An' 'ouses both sides of the street,
And 'edges two sides of the lane,
And the parson an' gentry between,
An' touchin' my 'at when we meet --
  Me that 'ave been what I've been?

Me that 'ave watched 'arf a world
'Eave up all shiny with dew,
Kopje on kop to the sun,
An' as soon as the mist let 'em through
Our 'elios winkin' like fun --
Three sides of a ninety-mile square,
Over valleys as big as a shire --
Are ye there? Are ye there? Are ye there?
An' then the blind drum of our fire . . .
An' I'm rollin' 'is lawns for the Squire,
Me!

Me htat 'ave rode through the dark
Forty mile, often, on end,
Along the Ma'ollisberg Range,
With only the stars for my mark
An' only the night for my friend,
An' things runnin' off as you pass,
An' things jumpin' up in the grass,
An' the silence, the shine an' the size
Of the 'igh, unexpressible skies --
I am takin' some letters almost
As much as a mile to the post,
An' mind you come back with the change!
Me!

Me that saw Barberton took
When we dropped through the clouds on their 'ead,
An' they 'ove the guns over and fled --
Me that was through Di'mond I'll,
An' Pieters an' Springs an' Belfast --
From Dundee to Vereeniging all --
Me that stuck out to the last
(An' five bloomin' bars on my chest) --
I am doin' my Sunday-school best,
By the 'elp of the Squire an' 'is wife
(Not to mention the 'ousemaid an' cook),
To come in an' 'ands up an' be still,
An' honestly work for my bread,
My livin' in that state of life
To which it shall please God to call
Me!

Me that 'ave followed my trade
In the place where the Lightnin's are made;
Twixt the Rains and the Sun and the Moon --
Me that lay down an' got up
Three years with the sky for my roof --
That 'ave ridden my 'unger an' thirst
Six thousand raw mile on the hoof,
With the Vaal and the Orange for cup,
An' the Brandwater Basin for dish, --
Oh! it's 'ard to be'ave as they wish
(Too 'ard, an' a little too soon),
I'll 'ave to think over it first --
Me!

I will arise an' get 'ence --
I will trek South and make sure
If it's only my fancy or not
That the sunshine of England is pale,
And the breezes of England are stale,
An' there's something' gone small with the lot.
For I know of a sun an' a wind,
An' some plains and a mountain be'ind,
An' some graves by a barb-wire fence,
An' a Dutchman I've fought 'oo might give
Me a job where I ever inclined
To look in an' offsaddle an' live
Where there's neither a road nor a tree --
But only my Maker an' me,
An I think it will kill me or cure,
So I think I will go there an' see.


=== 
 Richard B. LangleyE-mail: [EMAIL PROTECTED]  
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142  
 University of New Brunswick   Fax:  +1 506 453-4943  
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
=== 

Re: Heliograph

[Richard Langley]

And, as a geodesist, it would be remiss of me not to point out that the
heliograph was preceded by the heliotrope, a device to make survey stations
more visible from long distances, invented by the father of modern geodesy,
Carl Friedrich Gauss, in the early 1800s.
-- Richard Langley
   Professor of Geodesy and Precision Navigation

On Wed, 23 Jun 1999, Peter Mayer wrote:

Fernando Cabral wrote:

As far as I know, what you call heliograph we just call
mirror. Nevertheless, there can be other names and usages
if you check with the different armed forces and other people
with survival training.

As to me, the only name I know is really mirror, even for
those especially-made mirrors with a small hole in the centre
(to be used to collimate the light ray).

Again, since you can clearly use such a device to send
Morse code you can say you write  with the sunlight,
than calling it heliograph should  not be unacceptable.

   I'm attaching a tiny JPEG illustration, taken from an ancient
dictionary, which accompanies the definition of 'heliograph'.  The
instrument definitely has a mirror! But as you'll see, it also incorporates
a telegraph key and a sighting vane.  My recollection is that they were
used by military forces in the 19th century in places like India.  (I have
a half-baked recollection that Kipling refers to one in a poem...?Is that a
source?!)

   cheers,

   Peter



=== 
 Richard B. LangleyE-mail: [EMAIL PROTECTED]  
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142  
 University of New Brunswick   Fax:  +1 506 453-4943  
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
=== 

Re: Urgent request.

[Richard Langley]

Ecclesiastes. Chapter 3. Verse 11.  The online versions I checked did not
capilalise his.

On Mon, 17 May 1999, Tony Moss wrote:

Fellow Shadow Watchers,
This is 100% on topic and somewhat urgent for me. 
 The large bronze dial plate which I am about to engrave must bear the 
biblical inscription 

He hath made every thing beautiful in his time 

Can anyone give me 'chapter  verse' for this please as I must be certain 
that I have it absolutely per the King James' version as erasers don't 
work on bronze :-)  In particular does 'his' have a capital letter?

Before now I've made a mistake in the workshop and found myself mentally 
reaching for 'undo'.

If only it were possible!

Many thanks in advance.

Tony Moss


   



=== 
 Richard B. LangleyE-mail: [EMAIL PROTECTED]  
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142  
 University of New Brunswick   Fax:  +1 506 453-4943  
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
=== 

Re: update on Schmoyer sundial

[Richard Langley]

I'm not a member but here's the contact info:

Dr. Andre Bouchard, Secretaire General
La Commission des Cadrans solaires du Quebec
42, av. de la Brunante
Outremont (Montreal)
Quebec  H3T 1R4
Canada

tel: 514-341-3997
fax: 514-341-3997
e-mail: [EMAIL PROTECTED]


On Tue, 11 May 1999 [EMAIL PROTECTED] wrote:

Dear Prof. Langley

At 12:09 PM 5/10/99 -0700, you wrote:
Perhaps there are some members from the Quebec Sundial Society (La
Commission des Cadrans solaires du Quebec) on the list. If not, I could put
you in touch with the society.  Perhaps they would be willing to help.

Thank you - that is an excellent suggestion!
I checked the home page of the society (French only) and could not find 
a link to contact the society. Please do give me a contact with them.
If it is possible for you (as a member?) to lay a bit of groundwork for
me, I would greatly appreciate it.

Dave Gagnon




=== 
 Richard B. LangleyE-mail: [EMAIL PROTECTED]  
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142  
 University of New Brunswick   Fax:  +1 506 453-4943  
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
=== 

Re: bad people on the list

[Richard Langley]

Is this really from Fernando?  Doesn't sound like it.  Note that the posting
did not origniate from his usual e-mail address but from Hot Mail.  Do we have
a Fernando imposter?
-- Richard Langley
   Professor of Geodesy and Precision Navigation

On Sat, 17 Apr 1999, Fernando Cabral wrote:

Hello to All.

  I hate to start something, but I think that Jim Morrison is a fraud. 
I have check his equations for EOT, and I believe that he just made 
them up. Here in Brasilia, we have a saying to translate which means, 
even a stupid man may be considered wise if he keeps his mouth shut.
If you don't know something Jim, than be graceful enough to ask for 
help for someone who does. But please don't make up non-factuous 
nonsense. I know that Jim is not a true dialist, that his interests 
are elsewhere, and maybe he is just jealous of the rest of us. I hope 
I have not to offend anyone, I'm just helping to keep everyone aware 
of the facts.

  Fernando

___
Get Free Email and Do More On The Web. Visit http://www.msn.com




=== 
 Richard B. LangleyE-mail: [EMAIL PROTECTED]  
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142  
 University of New Brunswick   Fax:  +1 506 453-4943  
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
=== 

Re: GPS war

[Richard Langley]

No difference.  See http://www.op.dlr.de/~igex98op/monitor/monitor.htm
-- Richard Langley
   Professor of Geodesy and Precision Navigation

On Fri, 26 Mar 1999, Tom Mchugh wrote:

Dear All,

Last year there was some discussion on the List concerning
possible changes of accuracy of GPS at the time U. S. was
staging air attacks in Africa  Afghanistan, but as I recall,
there was no difinitive opinion on that matter. In light of the
current U. S. war in Jugoslavia, can anyone confirm any
differences in GPS accuracy?


Tom McHugh

[EMAIL PROTECTED]

R. R. 1, Box 896
Fort Fairfield, ME 04742
USA

46? 45' 13
67? 48' 42



=== 
 Richard B. LangleyE-mail: [EMAIL PROTECTED]  
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142  
 University of New Brunswick   Fax:  +1 506 453-4943  
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
=== 

Even Further Off topic: transit of Venus in about 1770

[Richard Langley]

And for a discussion of the transit of Venus, teaching astronomy, and love,
read Stephen Leacock's short story The Transit of Venus. :-)

On Mon, 15 Mar 1999, Dave Bell wrote:

On Tue, 16 Mar 1999, John Pickard wrote:

 When I was a kid at school more years ago than I care to remember, I 
 was taught that Lieutenant James Cook RN came out to Australia in 
 1770 (or was it 1772??) to have a look around, and also to observe 
 the transit of Venus in Tahiti.
 
 So my question (which I am sure will be answered) is simple: why
 would anyone cross the road (let alone the world in a small sailing
 ship) just to see a ToV? 
 
 Thanks, John
 Dr John Pickard
 Senior Lecturer, Environmental Planning
 Graduate School of the Environment
 Macquarie University, NSW 2109 Australia

John:

  Your question intrigued me, as I had always just accepted the bare
statement, and hadn't thought about *why*, at least that I can recall.

  Certainly, one part of the question - why travel so far? is clear. The
event, like a lunar eclipse, is not visible from all parts of the Earth.
In fact, it is slightly more like a total solar eclipse, in that one's
position on the Earth affects the view, by parallax.

  The big question though, is Why did they care?. Seems the project was
basically to determine the radius of the Earth's orbit, still undetermined
in the late 18th century.

  Check out:

http://www.dsellers.demon.co.uk/index.htm

Dave




=== 
 Richard B. LangleyE-mail: [EMAIL PROTECTED]  
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142  
 University of New Brunswick   Fax:  +1 506 453-4943  
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
=== 

Re: GMT and UTC

[Richard Langley]

Some of the recent postings on GMT and UTC contain inaccuracies and
half-truths. It was to set the record straight that I wrote the article on GMT
and UTC in the first place.  It's enough to drive a professor to drink (feel
free to send some 18 yr. Macallan single malt!).  For those who haven't yet
had a chance to read my article:
1) UTC is not a French acronym. They used to use TUC as an acronym but they
now use UTC along with everyone else.  Before UTC, we had UT0, UT1, and UT2.
So it was obvious that Coordinated Universal Time should be UTC and not CUT.
2) When the Gregorian calendar was introduced in 1582, 10 days were dropped.
For a good on-line reference to calendar issues see Claus Tonderings's
Frequently Asked Questions about Calendars:
http://www.pip.dknet.dk/~pip10160/cal/calendar20.html.
3) UT1 does not vary due to polar motion but only due to changes in the
earth's spin.  The effect of polar motion is, however, in UT0.
4) GMT, if U.K. standard time is meant (which is the usual case when the term
GMT is used these days), is EXACTLY the same as, and therefore equally as
accurate as, UTC. (Different timing labs around the world maintain different
versions of UTC and through clock comparisons, chiefly using GPS, a definitive
UTC is maintained by the Bureau International des Poids et Mesures).
5) Perhaps the use of GMT as a synonym for UT1 should be deprecated.
6) UTC is actually adjusted for leap seconds, not TAI.  A plot of UTC vs. TAI
over the years shows the leap second jumps.
-- Richard Langley
   Professor of Geodesy and Precision Navigation

=== 
 Richard B. LangleyE-mail: [EMAIL PROTECTED]  
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142  
 University of New Brunswick   Fax:  +1 506 453-4943  
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
=== 

British Millennium Time Stamp

[Richard Langley]

I don't think I saw mention on the sundial or navigation lists of one of the
Royal Mail's new millennium stamps.  The 20p stamp issued on 12 January is
called Timekeeping and was one of 4 stamps featuring British inventors and
inventions released that day (there will be 48 millennium stamps in all on
different themes). The stamp stylistically features Harrison's chronometer and
the Greenwich meridian line.  Image and description available at
http://www.royalmail.co.uk/athome/stamps/jan.htm.  The image resolution
isn't very good. Would anyone care to do a high resolution scan of the stamp
and make it available to list members?

-- Richard Langley
   Professor of Geodesy and Precision Navigation

=== 
 Richard B. LangleyE-mail: [EMAIL PROTECTED]  
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142  
 University of New Brunswick   Fax:  +1 506 453-4943  
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
=== 

Re: Blue Moon

[Richard Langley]

The moon (and sun) can appear blue (or green) due to dust particles in the
atmosphere following large volcanic explosions.  Smoke from forest fires can
produce a similar effect.  Smoke from forest fires in Canada can reach Europe.
One such fire in September 1950 produced smoke that caused blue moons to be
seen in Europe.  Tony, how old are you?  Could this have been your event?
-- Richard Langley
   Professor of Geodesy and Precision Navigation
P.S. Source of info: The Stars Belong to Everyone by Prof. Helen Sawyer Hogg
(a famous and much-loved Canadian astronomer (she passed away in 1993 at age
87).

On Sat, 30 Jan 1999, Tony Moss wrote:

Fellow Shadow Watchers,

As a child I remember running into the house to say that the full moon 
looked blue in colour.  Everyone laughed although nobody went outside to 
look for themselves.  As I recall this was confirmed as a rare occurrence 
on the radio the following day much to my parents' surprise.  Ever since 
then I've assumed that this was the origin of the saying 'once in a blue 
moon'.

On TV yesterday I heard that we are about to witness a 'blue moon', 
explained as the rare occurrence of two full moons within one calendar 
month - nothing to do with colour at all.

Was my experience just a childhood fantasy?

Tony Moss



=== 
 Richard B. LangleyE-mail: [EMAIL PROTECTED]  
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142  
 University of New Brunswick   Fax:  +1 506 453-4943  
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
=== 

Re: Latitude/Longitude

[Richard Langley]

There's a difference between astronomical latitude and longitude and geodetic
latitude and longitude.  Prof. Charles Merry at the University of Cape Town
should be able to help you out with the specifics of geodetic datums used in
South Africa: [EMAIL PROTECTED]
-- Richard Langley
   Professor of Geodesy and Precision Navigation

On Wed, 13 Jan 1999, Anton Reynecke wrote:

Apologies for this non-sundial question, but I do hope someone can help.

I've always been under the impression that Latitude/Longitude is a universal
and unambigious method of indicating a position on the earth but now I am
not so sure

In South-Africa, the National survey system is based on a Gauss conform
system with the Clarke 1880 (Modified) Ellipsoid.

It is fundamentaly the same as the wordwide UTM system, with a slightly
different scale factor, and the width of a system is only two degrees in
longitude, one on either side of a central meridian, whereas  UTM covers six
degrees.

Now the National system is based on the the same projection but we are using
the WGS 84 ellipsoid.

That caused the Latitude of a fixed point to increase South by 2,04 arc
seconds, and Longitude West by 1,06 arc seconds (approximately), and the
projected co-ordinates changed by approx. 296 metres South and 27 metres
West (Differences calculated by comparing coordinates from the old system
with the new system, around Pretoria).

I am under the impession that Lat/Long is astronomically fixed from distant
objects, with the origin being the rotation axis of the earth, so how can
the values be influenced by adopting a new ellipsoid ?

What fundamentals am I missing?


D. Anton Reynecke









=== 
 Richard B. LangleyE-mail: [EMAIL PROTECTED]  
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142  
 University of New Brunswick   Fax:  +1 506 453-4943  
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
=== 

Re: GPS under interference?

[Richard Langley]

GPS has been under Selective Availability since it was declared operational.
This limits horizontal positional accuracy to 100 metres at the 95% confidence
level.  See http://www.cnde.iastate.edu/staff/swormley/gps/check_sa.html for
more info.
-- Richard Langley
   Professor of Geodesy and Precision Navigation


On Mon, 21 Dec 1998, Fernando Cabral wrote:

Hello


This morning I was trying to set my watch using my GPS. Taking a fix in
my
backyard I noticed the position reported was displaced about
100 meters to the East (Latitude was the same). It aroused my
curiosity. I took the GPS to my office and read it again.
I found about 80 meters to the East again.

This error seemed too big and too systematic to be taken
as an accident. Could it be the case that the American
government is lowering the GPS precision because of
the war? Has any one noticed any similar behaviour?

- fernando


--
Fernando Cabral Padrao iX Sistemas Abertos
mailto:[EMAIL PROTECTED]  http://www.pix.com.br
mailto:[EMAIL PROTECTED]
Fone: +55 61 321-2433   Fax: +55 61 225-3082
15? 45' 04.9 S 47? 49' 58.6 W
19? 37' 57.0 S 45? 17' 13.6 W





=== 
 Richard B. LangleyE-mail: [EMAIL PROTECTED]  
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142  
 University of New Brunswick   Fax:  +1 506 453-4943  
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
=== 

Re: GPS under interference?

[Richard Langley]

Remember, SA is a quasi-random variation.  Sometimes, the instantaneous SA
error is 0.  Did you monitor the position for at least 15 minutes?  To the
best of my knowledge, the U.S. military no longer has the need to turn off SA 
durirng operations.
-- Richard Langley
   Professor of Geodesy and Precision Navigation

On Mon, 21 Dec 1998 [EMAIL PROTECTED] wrote:


On Mon, 21 Dec 1998, Fernando Cabral [EMAIL PROTECTED] wrote:

...This error seemed too big and too systematic to be taken
as an accident. Could it be the case that the American
government is lowering the GPS precision because of
the war? Has any one noticed any similar behaviour?

Hi Fernando,

I had the same thought, so last week in the first hours of the bombing I 
checked 
my own GPS receiver.  I found the GPS position to agree perfectly with the 
topographic map position of my backyard (to the nearest arcsecond in both 
coordinates, the limit of the display).  Usually one of the numbers differs in 
the last digit, but not that night!

-- Roger
 **
 |  Roger W. Sinnott  |
 |  Associate Editor  |
 |  Sky   Telescope  |
 **



=== 
 Richard B. LangleyE-mail: [EMAIL PROTECTED]  
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142  
 University of New Brunswick   Fax:  +1 506 453-4943  
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
=== 

Re: magnetic variation software

[Richard Langley]

The magnetic declination changes slowly with time. The Geological Survey of
Canada's on-line magnetic declination calculator gives for your coordinates:
1995  10d 11m W
1998  10d 22m W
2000  10d 30m W
You can get a DOS or Windows program for do-it-yourself use at
http://geomag.usgs.gov/
-- Richard Langley
   Professor of Geodesy and Precision Navigation


On Wed, 11 Nov 1998, Greg Milsom wrote:

Is anyone aware of a shareware or freeware program available on the web
that will compute the magnetic variation for various Longitude and
Latitude coordinates? I am trying to orient my homemade dial and come up
with slightly different variations depending on who I talk to.  Anywhere
from 9d W to 10.7d W.  My coordinates are 39d N and 77d W.  Is there a
'simple' or maybe not so simple formula that I could program an Excel
spreadsheet to calculate. Thanks.
-- 

Fiddler's Green
We Design and Install Renewable Energy Systems
Solar Energy...Live the Good Life!
Greg Milsom, Owner
PO Box 1200
Bowie,  Maryland  20718
Phone/Fax:  (301) 210-7669
http://www.radix.net/~green



=== 
 Richard B. LangleyE-mail: [EMAIL PROTECTED]  
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142  
 University of New Brunswick   Fax:  +1 506 453-4943  
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
=== 

Re: Radius of the Earth

[Richard Langley]

The prime vertical radius of curvature of the ellipsoid (the radius of the
osculating circle in the east-west direction) is given by

 a^2
N = ---
(a^2 * (cos phi)^2 + b^2 * (sin phi)^2)^0.5

The ellipsoid of the Geodetic Reference System 1980 has

a = 6 378 137 metres
b = 6 356 752 metres (to the nearest metre).

In computing the distance to the horizon, if you want the visibile horizon (as
opposed to the geometric one), you should take refraction into account.

-- Richard Langley
   Professor of Geodesy and Precision Navigation



where a and b are the semimajor and semiminor axes of the ellipsoid and phi is
the geodetic latitude.

On Mon, 3 Aug 1998, Tony Moss wrote:

Fellow Shadow Watchers,
   Information boards are being prepared for a 
 nearly-completed large dial on a hill near the Northumberland (UK) coast 
 which is 94 metres above mean sea level at Latitude  55ƒ 1' 38 North  
 Longitude  1ƒ 30' 16 West.

 The latest question is How far away is the sea horizon?  School geography 
 taught me that the earth is an 'oblate speroid' so I suppose the true 
 distance varies slightly depending on the direction in which the observer is 
 looking but so little as to be unimportant perhaps?  The sea is only visible 
 in a generally easterly direction.

Can any list member supply the mean sea level radius of the earth at this 
location on which to base the necessary trig calculation plus any subtleties I 
may have overlooked as I don't have ready access to specialist reference 
material of this sort.

With thanks in anticipation of any helpful response.

Tony Moss




=== 
 Richard B. Langley Internet: [EMAIL PROTECTED] or 
[EMAIL PROTECTED]  
 Geodetic Research Laboratory   BITnet:   [EMAIL PROTECTED] or 
[EMAIL PROTECTED]
 Dept. of Geodesy and Geomatics Engineering Phone:(506) 453-5142
 University of New BrunswickFAX:  (506) 453-4943
 Fredericton, N.B., Canada  E3B 5A3 Telex:014-46202 
  Fredericton?  Where's that? See: http://www.city.fredericton.nb.ca/
=== 

Re: Magnetic North Pole

[Richard Langley]

On Fri, 7 Nov 1997, k.schwarzinger wrote:

 Dear all,
 
 is there in the INTERNET a website, which gives informations
 about the curent value from the declination of the magentic
 North Pole ?
 
 Are there still informations about the situation of the magnetic
 North Pole ( INTERNET or literature ) ?
 
 Thanks for any help.
 
 Regards
 Karl.

http://www.geolab.nrcan.gc.ca/geomag/e_cgrf.html

=== 
 Richard B. Langley Internet: [EMAIL PROTECTED] or 
[EMAIL PROTECTED]  
 Geodetic Research Laboratory   BITnet:   [EMAIL PROTECTED] or 
[EMAIL PROTECTED]
 Dept. of Geodesy and Geomatics Engineering Phone:(506) 453-5142
 University of New BrunswickFAX:  (506) 453-4943
 Fredericton, N.B., Canada  E3B 5A3 Telex:014-46202 
  Fredericton?  Where's that? See: http://www.city.fredericton.nb.ca/
=== 

Re: log tan calculations on a pocket calculator

[Richard Langley]

On Tue, 24 Jun 1997, Tony Moss wrote:

 As a dial maker and reluctant 'number cruncher' I use computer spreadsheets
 for all my calculations but have had to rely on my old printed six-figure
 tables for one remaining job - the log tan values in the sun's azimuth
 calculation.
 
 e.g. My printed tables give the log tan of 25ƒ as  9.668 673  Can I use my

9.668 673 = 10 + log tan 25 degrees; i.e., 10 + (-0.331327)

Does that help at all?

 Casio fx 85s Scientific pocket calculator to achieve this result or do I
 need a special type of calculator?  No combination of keystrokes I've tried
 produces anything like that figure and, like Pooh Bear, my brain is
 starting to hurt.
 
 What am I doing wrong?
 
 Hoping someone out there can offer guidance with a 'mystery sundialling
 gift' as a 'thank you' for the first correct solution!!
 
 Tony


=== 
 Richard B. Langley Internet: [EMAIL PROTECTED] or 
[EMAIL PROTECTED]  
 Geodetic Research Laboratory   BITnet:   [EMAIL PROTECTED] or 
[EMAIL PROTECTED]
 Dept. of Geodesy and Geomatics Engineering Phone:(506) 453-5142
 University of New BrunswickFAX:  (506) 453-4943
 Fredericton, N.B., Canada  E3B 5A3 Telex:014-46202 
  Fredericton?  Where's that? See: http://www.city.fredericton.nb.ca/
=== 

Re: Archiving Sundial List Postings

[Richard Langley]

On Mon, 24 Feb 1997, Mark Gingrich wrote:

 I just ran across a service that might be of value to this mailing
 list.  There's an outfit called Reference.com that will archive our 
 postings, much like DejaNews does with Usenet's traffic.  Previous
 postings then can be searched and retrieved with your Web browser.
 For more details, check out
 
  http://www.reference.com
 
 I, for one, would welcome this, as it would save me from having to
 store the ever-expanding collection of valuable messages on my hard
 disk.  In addition, if late-comers to the mailing list ask questions
 about items already discussed, we can refer them to the on-line archive
 and avoid a reposting.
 
 Does anyone (in particular Daniel Roth) have any objection to this
 proposal?  If not, I'll gladly subscribe the Sundial mailing list
 later this week.
 
 ~~
  Mark Gingrich  [EMAIL PROTECTED]  San Leandro, California
 ~~

Would it be possible to have the old messages added?  I think I've stored
almost all of the list messages (about 611) in a Unix PINE mail file.  Let
me know if it would be of use.
-- Richard Langley

=== 
 Richard B. Langley Internet: [EMAIL PROTECTED] or 
[EMAIL PROTECTED]  
 Geodetic Research Laboratory   BITnet:   [EMAIL PROTECTED] or 
[EMAIL PROTECTED]
 Dept. of Geodesy and Geomatics Engineering Phone:(506) 453-5142
 University of New BrunswickFAX:  (506) 453-4943
 Fredericton, N.B., Canada  E3B 5A3 Telex:014-46202 
Fredericton?  Where's that? See: http://degaulle.hil.unb.ca/NB/fredericton.html 
=== 

Re: E-mail adress of Mozart::Edelmann

[Richard Langley]

On Sat, 8 Jun 1996, Fer J. de Vries wrote:

 To Mozart::Edelmann.
 
 I got an E-mail from
 MOZART::EDELMANN[EMAIL PROTECTED]
 but returning an answer to this adress I got the message back.
 What is wrong with this adress?
 
 
 Fer de Vries.
 
 [EMAIL PROTECTED]
 

In the subscriber list, this person is listed as

MOZART::EDELMANN [EMAIL PROTECTED]

Note that MOZART::EDELMANN is a DECnet style address (user EDELMANN on
host MOZART).  Use the address 

[EMAIL PROTECTED]

which includes a gateway to DECnet.


=== 
 Richard B. Langley Internet: [EMAIL PROTECTED] or 
[EMAIL PROTECTED]  
 Geodetic Research Laboratory   BITnet:   [EMAIL PROTECTED] or 
[EMAIL PROTECTED]
 Dept. of Geodesy and Geomatics Engineering Phone:(506) 453-5142
 University of New BrunswickFAX:  (506) 453-4943
 Fredericton, N.B., Canada  E3B 5A3 Telex:014-46202 
Fredericton?  Where's that? See: http://degaulle.hil.unb.ca/NB/fredericton.html 
=== 

Re: Problems downloading Brad Lufkins Sundial program

[Richard Langley]

On Mon, 13 May 1996, John D. Hall wrote:

 Can anybody provide a temporary ftp site for a Mac version of Brad
 Lufkins Sundial program. After repeated attempts I have been unable
 to download it from him (files I receive range in size from (950K
 down to 226K) I would love to get a copy of this program but so far
 no luck. Can anybody help ?
 
 If anybody is interested in a program (Mac only) for drawing stero
 sunpath diagrams and the calculation of HSA and VSA angles on
 buildings please look at SketchPAD on our web site at:
 
 http://www.arch.utas.edu.au
 
 Follow the lead until you come to the software page.
 
 John Hall
 

I have placed a BinHexed copy of the self-extracting archive of Brad
Lufkin's program on one of our anonymous ftp servers. You can retrieve the
file using the following URL:

file://sputnik.gge.unb.ca/pub/sundials.hqx

=== 
 Richard B. Langley Internet: [EMAIL PROTECTED] or 
[EMAIL PROTECTED]  
 Geodetic Research Laboratory   BITnet:   [EMAIL PROTECTED] or 
[EMAIL PROTECTED]
 Dept. of Geodesy and Geomatics Engineering Phone:(506) 453-5142
 University of New BrunswickFAX:  (506) 453-4943
 Fredericton, N.B., Canada  E3B 5A3 Telex:014-46202 
Fredericton?  Where's that? See: http://degaulle.hil.unb.ca/NB/fredericton.html 
=== 

Re: Earliest sunset

[Richard Langley]

On Fri, 3 May 1996, Jack Aubert wrote:

 I would like to forward the following enquiry to all those dialiasts
 who know more than I do about celestial mechanics.  It seems to me
 that the answer has something to do with the fact that the sun appears 
 as a disk rather than a point in space, but I don't know enough to think
 this through logically.  The question was posed by  Rory Sellers 
 ([EMAIL PROTECTED]).  What exactly does he have to do to subscribe 
 to the sundial list?  
 
 Many years ago a golf-playing uncle in Los Angeles asked me why it was 
 that the shortest day of the year was the winter solstice, but the sun 
 actually set earliest on about Dec. 13 (he had noticed that he could get 
 in an extra hole of golf on Dec. 21 -- I'm not making this up.)
 
 After a lot of research (there was no Web then!) I realized the answer 
 had to do with the equation of time, the difference between solar and 
 sideral days, and mean solar time (and no doubt you know more about this 
 than I do.)
 
 So I told my uncle this, and the family got down to accomplishing other 
 life-tasks. Unfortunately, I recently realized that this explanation 
 must be false. This came about by looking more closely at an analemma on 
 a globe. If I am not mistaken, the analemma describes not only the 
 difference between mean and clock-time (due to the eccentricity of the 
 earth's orbit being non-zero) but also the (I guess arbitrary) dates on 
 which our clock is set. I.e. when the official timekeepers say that 
 the annual clock is zeroed. And here, I was shocked to see a) that this 
 date seems to be the winter solstice; and b) that I had never noticed 
 this before!
 
 You see, I always knew that the earth was moving fastest around 
 Christmas time (near perihelion) and so I figured it made sense that the 
 clock was furthest out of whack around this time. And sure enough, 
 consulting either an almanac or a St. Joseph's Aspirin calendar, one can 
 see that the sun indeed sets earliest on Dec. 13, not Dec. 21. BUT HOW 
 IS THIS POSSIBLE, IF THE CLOCK IS ZEROED ON THE SOLSTICE? Shouldn't 
 the equation of time being equal to zero on Dec. 21 mean that the sun 
 should set the earliest on that date, too?
 
 Please help! A family conundrum that I thought we had settled twenty 
 years ago is now bothering me!


I believe it is the equation of time that is responsible for the
difference.  Let's consider the sun to be a point (taking into account the
sun's semi-diameter won't affect us too much).  When the sun is on the
horizon (actually sunset occurs when the refracted upper limb of the sun
is on the horizon, but as I said we won't worry about this detail), the
local hour angle of the true sun is given by

 cos(H) = -tan(lat) * tan(delta)

where lat is the latitude of the place and delta is the sun's declination.
The hour angle of the true sun is equal to the hour angle of the mean sun
plus the equation of time and the hour angle of the mean sun is equal to
mean solar time minus 12 hours.  So,

 H = H_m + E = MT -12h + E/60

where E is in minutes.

So, MT of sunset, in hours, is given by

MT = 12h - E/60 + acos(-tan(lat)*tan(delta))/180*12.

Now, consider first a point on the equator:

MT = 12h - E/60 + 6h = 18h - E/60.

Notice that this equation is independent of the sun's declination,
except via E.  The earliest sunset will occur when E is largest.  This
happens around 3 November.

If we re-do the calculation for Los Angles, with latitude of about 34
degrees, we find that the earliest sunset occurs around 6 December.  Note
that we have to take into account both the time variation of E and the
sun's declination.

=== 
 Richard B. Langley Internet: [EMAIL PROTECTED] or 
[EMAIL PROTECTED]  
 Geodetic Research Laboratory   BITnet:   [EMAIL PROTECTED] or 
[EMAIL PROTECTED]
 Dept. of Geodesy and Geomatics Engineering Phone:(506) 453-5142
 University of New BrunswickFAX:  (506) 453-4943
 Fredericton, N.B., Canada  E3B 5A3 Telex:014-46202 
Fredericton?  Where's that? See: http://degaulle.hil.unb.ca/NB/fredericton.html 
=== 

Re: Compendium graphics

[Richard Langley]

On 26 Mar 1996, Fred Sawyer wrote:

 Ken,

 The quick answer is that there is no mechanism within the compendium for
 printing graphics.  Many members subscribe to both print and digital issues -
 one of the advantages of the print issue being that you get a printout of the
 graphics.  Of course if you want your own hardcopy outside the issue, you have
 to turn to a photocopy machine.  Similarly for the digital issue, you can use
 any of a number of good graphics screen capture utilities which will turn the
 graphic that appears on your screen into a PCX or GIF file which can then be
 printed.  Many of our graphics start out as HPG or PLT files, which are much
 more easily sized and scaled - but sending these formats would require that I
 package all of the graphics separately - and the current material has already
 been filling each disk even after being compressed.

 If there's a particular graphic you are interested in, let me know.

 Fred Sawyer





For the future, perhaps a different format could be used such as Adobe
PDF.  These documents look good both on screen and when printed.
-- Richard Langley
   Professor

===
 Richard B. Langley Internet: [EMAIL PROTECTED] or 
[EMAIL PROTECTED]
 Geodetic Research Laboratory   BITnet:   [EMAIL PROTECTED] or 
[EMAIL PROTECTED]
 Dept. of Geodesy and Geomatics Engineering Phone:(506) 453-5142
 University of New BrunswickFAX:  (506) 453-4943
 Fredericton, N.B., Canada  E3B 5A3 Telex:014-46202
Fredericton?  Where's that? See: http://degaulle.hil.unb.ca/NB/fredericton.html
===

Re: GNOMONICS in the WWW

[Richard Langley]

On Thu, 15 Feb 1996, Daniel Roth wrote:

 
 GNOMONICS in the WWW
 
 
 I've tried to search for some pages in the WWW concerning sundials. One
 problem is that there is a Internet provider called Sundial Systems or
 similar. So, when one enters the word 'sundial' into some of the search
 engines like Lycos or WebCrawler one gets tons of links to pages which
 don't have to do with sundials.
 
 So far I've found the following links:
 
 Walter Scott Houston Memorial Sundial at Wesleyan University
 http://sun.astro.wesleyan.edu/sundial.html
 
 Sundial as a gift (commercial)
 http://www.save.com/ggifts/page_65.html
 
 Science Museum Galleries - Time Measurement
 http://www.nmsi.ac.uk/galleries/time.html
 
 Wing Sundial (commercial)
 http://www.isn.net/wxsense/sund_idx.html
 
 CLOCKS and TIME by Gordon Uber
 http://glen-ellyn.iit.edu/~clocks/clocks/sundial/sundial.html
 
 Sundial Theory
 http://cpcug.org/user/jaubert/jsundial.html
 
 Richard D. Swensen Sundial
 http://bugs-bunny.anetsrvcs.uwrf.edu:80/sundial/
 
 And you may try my own page http://www.ph-cip.uni-koeln.de/~sonnenuhr.html
 I'm sorry these pages are in german only. If I have time I want to translate
 and enlarge them.
 
 Has anyone found other gnomonic links?
 
 - Daniel
 

RGO Information Leaflet No. 23: 'Sundials'
http://www.ast.cam.ac.uk/RGO/leaflets/sundials/sundial.html

Sundial of Hong Kong University of Science and Technology:
http://sunsite.ust.hk/hkust/campus/sundial.html

-- Richard Langley
   Professor

=== 
 Richard B. Langley Internet: [EMAIL PROTECTED] or 
[EMAIL PROTECTED]  
 Geodetic Research Laboratory   BITnet:   [EMAIL PROTECTED] or 
[EMAIL PROTECTED]
 Dept. of Geodesy and Geomatics Engineering Phone:(506) 453-5142
 University of New BrunswickFAX:  (506) 453-4943
 Fredericton, N.B., Canada  E3B 5A3 Telex:014-46202 
Fredericton?  Where's that? See: http://degaulle.hil.unb.ca/NB/fredericton.html 
=== 

Re: GNOMONICS in the WWW

[Richard Langley]

On Thu, 15 Feb 1996, Richard Langley wrote:

 RGO Information Leaflet No. 23: 'Sundials'
 http://www.ast.cam.ac.uk/RGO/leaflets/sundials/sundial.html

Sorry, should be

http://www.ast.cam.ac.uk/RGO/leaflets/sundials/sundials.html


=== 
 Richard B. Langley Internet: [EMAIL PROTECTED] or 
[EMAIL PROTECTED]  
 Geodetic Research Laboratory   BITnet:   [EMAIL PROTECTED] or 
[EMAIL PROTECTED]
 Dept. of Geodesy and Geomatics Engineering Phone:(506) 453-5142
 University of New BrunswickFAX:  (506) 453-4943
 Fredericton, N.B., Canada  E3B 5A3 Telex:014-46202 
Fredericton?  Where's that? See: http://degaulle.hil.unb.ca/NB/fredericton.html 
===