Does anyone know how to figure the length of a spiral line, given only the
width between the lines and the diameter. or the radii of the circle
I think this is underspecified; what spiral? Do you have a formula
for the curve?
Jim
===
He who wonders discovers that this in itself is wonder.
Help!
I'm working on an Excel spreadsheet and need a formula or function that
will give,
for an input A and B, the sum of all the powers of A for integers from
1 to B.
Example: 1.05 + 1.05 squared + 1.05 cubed ...
Can anyone help me?
-- Tad Dunne
This is called the geometric
If one is to delve into the question of What is time? it may be
worth asking the companion question What is space? The theory of
relativity tells there is a deep connection between the two. And the
fact that the spatial question is asked less frequently may imply that
it is an even subtler
In fact the situation is further complicated by polar motion. The
earth's axis of rotation differs from its axis of figure (the maximum
moment of inertia). The rotation axis moves slowly around the axis of
figure in a quasi-circular path. The maximum amplitude of the polar
motion is typically
Here is the eclipse info from the 1999 Astronomical Almanac (p. A 79).
I meant to include this in the last message, but sent it off too
soon...
Circumstances of the Eclipse
d h m s
UT of geocentric opposition in right ascension,
Well, that's interesting. I would have defined full moon as the
time when the moon is most nearly opposite the sun, which would be the
same as the time of maximum ecclipse. How else can it be defined?
There must be something like a projection into the ecliptic.
Art Carlson
Perhaps the
Earalier I wrote:
Now we know from my earlier messages that the Moon
is one degree north of the ecliptic at the time of the full moon, and
approaching crossing.
Oops... It's south of the ecliptic at the time of the full moon.
Sorry for the error.
Jim
---
Dear Dialists...
Regarding the assertion by David Higgon that the Earth makes a better clock
than the frequency of an arbitrarily chosen atom. Unfortunately Earth's
rotation is slowing down, so the atom is preferable, though admittedly less
romantic. Presumably, if the human timekeepers
Earlier I wrote:
The Explanatory Supplement to the Astronomical Almanac, mentions
alternatives to atomic time under study that may offer
improvements. (I don't have the book handy and cannot recall what they
are. I will try to post a follow-up on Monday.) I believe that
atomic timing
[EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] wrote:
snip
...as the time of sunset varies by as much as 6 hours from
solstice to solstice (here in Michigan).
end snip
Hmmm... can someone help me out? A quick check of my astrolabe,
with a plate for St. Paul, MN, gives sunset at about
Mike Shaw I am rather disappointed to learn that there isn't an
Mike Shaw actual pole sticking out of the earth at the South pole to
Mike Shaw mark the spot. I wonder if there is one at the North pole?
Mike Shaw It would be really neat to drop an equatorial dial plate
Mike Shaw over it and
Jean Meeus's book Mathematical Astronomy Morsels
http://www.amazon.com/exec/obidos/ASIN/0943396514/o/qid=921164695/sr=2-1/002-5697572-2293064
lists months over a period of about two hundred years which are
missing a lunar phase. I believe it lists 1961 as the previous year
(before this one)
The following are the years from 1800 to 2100 in which February has no
full moon. This is taken from Meeus's book.
180919152018
184719342037
186619612067
188519992094
Jim
--- --
Hello all:
Will two full moons always occur in a March that follows a Febuary with no
full moon?
John Carmichael
Tucson
The second March full moon this year occurs at 22:49 UT. Therefore,
if one moves east from London by a couple of time zones March has but
a single full moon this
This reasoning relies on the mean length of a lunation. But the
actual case is more complicated. See my reply to John on this same
subject.
Jim
--- --
| Jim Cobb | 540 Arapeen Dr. #100 | [EMAIL PROTECTED] |
| Parametric
Mark Wrigley [EMAIL PROTECTED] wrote:
Not quite true.
Last month Australia had a full moon at about 2am on Feb 1.
In Europe it was still January.
Quite so. Meeus (careful calculator that he is) explicitly notes his
use of UT (and the dependence of such a calculation on the time zone).
The
Does anyone know when the next Transit of Earth will occur (visible from
Mars)? Perhaps one of the upcoming Martian landers could view the event!
Troy Heck
Turning again to Meeus' excellent book:
1905 May 8
1984 May 11
2084 Nov 10
2163 Nov 15
2189
The 007 Capuchin Dial is a PostScript program written
initially by Eric MacPhereson, University of Manitoba and with a
later revision by Andrew J Irwin, c/o Math 007, University of
Toronto [...]
Luke,
Thank you for sending the info on the capuchin sundial. This looks
fascinating. It
Whenever you don't understand something, just reveal that ignorance to
many people and then perhaps you'll understand... At least, I think
that just happened to me. I think the key is that I don't cut out the
'slit and surrounding flap' completely, but leave it attached on the
side opposite the
Hello all:
Does anybody know the exact time (UT) when the Equation of Time equals zero
this April 15th (or is it the 16th)?
Thanks
John Carmichael
Tucson
I used the solver in xephem version 3.0 to find the zero of the
equation
Sun.HA+12-UT
(that's hour angle of the sun +
[EMAIL PROTECTED] wrote:
Hello John and everybody on this list,
I don't want to extend this discussion endlessly
, but I am surprised to read that the value of
EOT depends on longitude. [...]
I believe John was referring to the (local civil) date (and time) of
the occurrence of
they have a
case...
Jim_Cobb
--- --
| Jim Cobb | 540 Arapeen Dr. #100 | [EMAIL PROTECTED] |
| Parametric| Salt Lake City, UT | (801)-588-4632 |
| Technology Corp. | 84108-1202 | Fax (801)-588-4650
why don't you Anglophones try the metric system?
- fernando
Perhaps you should consider us bilingual in terms of units.
Technically inclined (and many other) Anglophones use both English and
SI units with comfort, though we prefer one set for some applications
and the other for others. I
Fernando wrote:
Now, I hate when I see something like 2 yards, 2 feet, 5 inches and
(the stroke of mercy) 1/8 -- It takes me several seconds to figure out
how tall that person is!
Now that's a tall specimen (2.57 meters)!
By the way: does stroke of mercy make sense in English?
-
Dave Bell [EMAIL PROTECTED] wrote (I believe tongue in cheek):
Indeed!
Why, just last night, I was working with furlongs and fifths of seconds...
Dave
It's interesting that you mention this. Over the last several weeks I
have been reading Tolkien's Lord of the Rings to my children. It
Gordon Uber [EMAIL PROTECTED] wrote:
Roger, thank you for your post. The Shadow Sharpener being a
pinhole camera, why not replace the gnomon with a pinhole? One then
could center a circle on the image and determine the time from its
position.
To form a good solar image the plane of the
[EMAIL PROTECTED] (John Carmichael) wrote:
Actually, nobody has mentioned this yet but as a kid I remember that
we used a pinhole to look at the image of a solar eclipse. Now I
know that it is called a shadow sharpener...
I remember many years ago during a partial eclipse looking at the
Earlier I wrote:
I remember many years ago during a partial eclipse looking at the
shade under a young tree. On the ground was a profusion of pinhole
images of the eclipsed sun, formed by the random gaps between the
leaves.
It occurs to me that I should have mentioned that the tree's shadow
Hi Jim,
Thanks for this wonderful unit of energy. I will use it in my next
technical presentation. It beats out my previous favourite, firkins per
fortnight (f/f).
Firkins per fortnight, a unit of volume flow, is most often used as a
measure of beer consumption by engineering students.
Luke Coletti [EMAIL PROTECTED] wrote:
For those interested the URL to Morrison Associates is listed below. I
certainly hope that one of the most famous of gnomon designs will be
recovered. Schmoyer's dial is a classic.
http://www.shepherdswatch.ca/
-Luke
Thanks for the link... These are
This kind of disclaimers are only found in the USA
and on products from the USA ;-)
-
Thibaud Taudin-Chabot, home email: [EMAIL PROTECTED]
(attachments max 500kB, in case of larger attachments contact me)
That should be ;-(
Arthur Carlson [EMAIL PROTECTED] wrote:
I do think being able to look at the sun and estimate directions could be
useful (in case you forgot to pack a compass, shame on you!). On my list of
things I would like to do and know how to go about but haven't found the
time is to investigate telling
A minute ago I wrote:
Except for a new (which you can't see) or full moon, you can use the
terminator as an indicator of a perpendicular direction to the plane
of the ecliptic. Follow the implied ecliptic to either horizon to get
a sense of east and west. If you're familiar with astronomy
Art Carlson wrote:
That's exactly what I had in mind. This is a rule that can be easily
understood and remembered, as opposed to remember to ADD nine hours to the
clock time for a three-quarter moon, if it is WANING. What I would like to
figure out is the errors involved in both methods,
http://bible.gospelcom.net/cgi-bin/bible?language=Englishversion=KJVpassage=Ecclesiastes+3:11matchno=7
Ecclesiastes 3:11 (English-KJV)
He hath made every thing beautiful in his time: also he hath set the
world in their heart, so that no
man can find out the work that God
I *really* like this scheme. Very clever...
Jim
--- --
| Jim Cobb | 540 Arapeen Dr. #100 | [EMAIL PROTECTED] |
| Parametric| Salt Lake City, UT | (801)-588-4632 |
| Technology Corp. | 84108-1202 |
Tom Semadeni ([EMAIL PROTECTED]) wrote:
Hi Jim^2,[Sorry, couldn't resist.]
Aren't we trying to lay out marks FROM a computer screen or a piece
of paper TO the real thing on the ground? So aren't we trying to
FIND the radii of the distance circles GIVEN the coordinates of
the target
I believe that for calculation by simple souls Easter is just the first
Sunday after the first full moon after the equinox of 21 March. But I
would like to find Easter several years ahead and do not know where to
find lunar phases except for the current year. Or is there a handy
table
Ciao a tutti!
I'm pleased to announce that my Web site is opened at the address:
http://web.tiscalinet.it/partena/index.htm
May be it's poor and ruogh, but it's just to begin with.
At the present it contains images of a few of my painted sundials.
Ciao
Angelo Brazzi
Thank you for
I thought this millennium's last summer solstice would be in December,
2000, south of the equator. Let's not forget our friends in oz,
Brazil, and other southern locales...
Jon, I'd like a copy too, if I may.
Jim
===
For a marketing boost, label your sundials as Y2K compliant. Hundreds
of
Dear Friends,
The North American Sundial Society is pleased to announce its new domain
and Home Page on the World Wide Web.
[...]
The URL is:
http://sundials.org
Best regards,
Bob Terwilliger
I was struck by the lighted flat map of the world on the page,
http://www.foxnews.com/js_index.sml?content=/etcetera/wires/0622/e_rt_0622_2.sml
World's Largest Sundial - But No Sun
Reuters 8:36 a.m. ET (1237 GMT) June 22, 1999
PARIS - France inaugurated the world's largest sundial Monday, using
an ancient Egyptian obelisk as the pin and Paris's famed Place
Robert Terwilliger [EMAIL PROTECTED] wrote:
Dear Friends,
The North American Sundial Society is pleased to announce its new domain
and Home Page on the World Wide Web.
We are releasing the URL to members of The Sundial Mailing List so they can
get a preview. Please visit the site and
Tony Moss [EMAIL PROTECTED]
In my impecunious searches of WWII 'surplus' stores back in the
1950s I came across a Portable Heliograph Set' in a pouch. It was
simply a mirror about f our inches across with a sighting hole in
the middle. A length of cord attache d it to a short rod with a
Bob Haselby [EMAIL PROTECTED] wrote:
Tony, This sounds like a signal mirror which were also contained
in life jackets etc as survival gear. The more modern are quite
effective and are great for annoying people on the beach. It uses
double internal reflection in the hole to give a virtual
I found a CNN item on the French sundial. It has more historical
information than the Fox News version.
http://www.cnn.com/TRAVEL/NEWS/9906/22/france.sundial.ap/
Jim
--- --
| Jim Cobb | 540 Arapeen Dr. #100 | [EMAIL PROTECTED]
Bob Haselby [EMAIL PROTECTED] wrote:
Jim, I found one of these signal mirrors in the surf years ago.
[description elided]
You will also see the light ball at that spot . Then move
your head and the mirror together until the spot lines up with the
distant object. As I recall you can
I cooked up a naive energy study for my home, Salt Lake City, to help
me explain to my children why it is hot in the summer and cold in the
winter. I used the xephem program as a calculator to compute the sine
of the sun's altitude at fifteen minute intervals over the course of
the day for March
There has been some discussion on this list of measuring time using a
sundial near a lunar eclipse (at the time the moon is 180 degrees away
from the sun and near the orbital node). Some may want to make
observations and report to this list. I, unfortunately, do not have a
high quality sundial.
Oops, I gave a bad URL in my last mail...
Here's what Merriam Webster online has to say
http://www.m-w.com/cgi-bin/dictionary
I should have pasted
http://www.m-w.com/home.htm
My apologies,
Jim
--- --
| Jim Cobb
You are correct that it is because the plane of the moon's orbit and
the plane of the earth's orbit around the sun differ. I recall that
the moon's orbital plane is inclined 5 or 6 degrees (not as
extreme as the inclination of the earth's poles, which is 23.5
degrees).
Here is a web site that
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
Can anyone give me a list of which USA States (or part-States), do NOT use
Daylight-Saving Time - e.g. Arizona doesn't, but which others also don't ?
Similarly, can anyone tell me what parts of Australia do NOT use Daylight-
Saving Time - I think Queensland doesn't, but are there some more
I suggest that only members of the list who are affected vote on this. If
you are like me and get your e-mail at work over a direct Internet
connection, you shouldn't care about attachments.
Of course I am affected by this decision. It matters a great deal to
me that the data comes in a
[EMAIL PROTECTED] wrote:
Just to correct an earlier error, all of Michigan observes daylight savings
time.
My apologies for handing out dated information. In the early
seventies when my brother attended Michigan State there was no
daylight savings time in Michigan. I'm curious when (and
Luke Coletti [EMAIL PROTECTED] wrote:
Greetings,
An interesting URL on Standard Time. Does anyone remember when in '73
we (USA) didn't observe DST?
http://www.standardtime.com/
-Luke
Yes, I remember it well, but your facts are wrong in one
particular--that year no standard
John Carmichael wrote:
p.s. Surprisingly enough, we're a little short on basic math related
questions. Any suggestions?
Why aren't the hour lines evenly spaced on a sundial? Of course the
intent here is for a horizontal (or vertical) dial, but the asker of
this question would probably not
for the dial, I thought
it would be a good test procedure.
Art Carlson wrote:
Jim_Cobb [EMAIL PROTECTED] writes:
I've thought of another tip for spotting worthless horizontal sundials
(such as is sold in garden shops, etc)--if the shadow of the gnomon
crosses the hour lines it's no good
Thibaud Taudin-Chabot [EMAIL PROTECTED] wrote:
The year 1800 wouldn't be a leap year under the Gregorian calendar because
18 is not a mutliple of 4.
Yes, this agrees with what I said about 1800 being treated as a normal
year in England as a result of her adoption the Gregorian reform.
May I recommend David Ewart Duncan's 'The Calendar' recently published by
4th Estate for an interesting insight into the calculation of the year etc.
Paul Murphy
I'll second that; it was a very good read.
The full title is
Calendar : Humanity's Epic
Frank Evans wrote:
but I believe many had to pay rent and leases early.
The law (in England) adopting the calendar change specified that this
was *not* to happen, though I would not be surprised if unscrupulous
landlords with uninformed tenants pulled off this trick anyway.
Here is some info concerning the Piet Hein dial I got from this list
some time back. Unfortunately, it appears that the URL has grown
stale...
Jim 40N45, 111W53
--- --
| Jim Cobb | 540 Arapeen Dr. #100 | [EMAIL PROTECTED]
I decided to get out xephem 3.0 and do some calculations for the
upcoming solstice/lunar perigee/full moon. Times are Mountain
Standard Time (UT - 7).
According to the xephem's solver, here are the time and other values
at the solstice (I found this by using the solver to minimize the
solar
Fernando Cabral wrote:
So, as far as I can see, all this fuss and hype about the next
new years day is but hype and fuss created and promoted by
marketers that wanna sell more hotel rooms, more air ticks,
more champaign...
I am wrong?
- fernando
No, I believe you are correct.
Clever
I'm not sure if Daniel Roth meant for each of us to vote on his
limitation suggestion, but if so, I vote for 50 KB.
Mac Oglesby
Ditto.
Jim
--- --
| Jim Cobb | 540 Arapeen Dr. #100 | [EMAIL PROTECTED] |
|
Dave Bell [EMAIL PROTECTED] wrote:
Try Russia: Not only do they have 5 (and somtimes more) grades at the
pump, up to 110 Octane (unheard of in the US since the 60's, except for
boats and aircraft), but a typical upper-middle grade, maybe 90 Octane,
sells for around 6 Rubles, about $0.23/14
Tony Moss [EMAIL PROTECTED] wrote:
The US of course still use Queen Anne's gallon which the Imperial
system replaced with a larger unit later on. We often forget this
when comparing fuel prices.
Tony Moss
I guess one could say that Queen Anne's gallon has outlived the
imperial gallon which
Hi moondialists:
I have been watching the waxing moon each night as it heads towards the
total lunar eclipse on January 21 4:41:30 Universal Time. Its apparent
diameter seems to be increasing, which means that it is approaching perigee,
right? If last month's huge full moon was nearly at
Earlier I wrote:
According to the 2000 Astronomical Almanac, perigee occurs Jan 19 23 h
UT. According to Kepler an orbital body moves fastest near perigee
(equal area rule). The faster motion may outweigh the larger umbra--I
don't know, though I suspect this to be the case.
On the web page
Does anybody there knows of any site
where I can get information about moonrise
and similar?
- fernando
Try
http://aa.usno.navy.mil/AA/data/docs/RS_OneYear.html
Jim 40N45, 111W53
--- --
| Jim Cobb | 540
I used xephem 3.2.3 to solve for when solar declination = 0.0 and got
2000 March 20 7:30:59 UTC. Xephem calculates that the declination of
the moon at that time to be 2:50:47.5 (degrees:minutes:seconds).
If you would give me your latitude and longitude I can compute the
azimuth of the moon at
The U.S. Naval Observatory
http://aa.usno.navy.mil/AA/data/docs/EarthSeasons.html
is a source I trust. It gives the following (precision to the minute)
d h d h m d h m
20002000
Perihelion Jan 3 05
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