Dear All,
Tomorrow, Friday 26 April at 16:00 UTC (17:00 BST), Frank King and Martins
Gills are hosting a Sundial Zoom Event. Here is the formal invitation:
Invitation...,
Frank King – BSS is inviting you to a scheduled Zoom meeting.
Topic: BSS March 2024 Bulletin Follow-up
Time: Apr 26, 2024
n the same direcion
as the light. I'll leave that as an exercise
for the reader :-)
Frank King
Cambridge, UK
---
https://lists.uni-koeln.de/mailman/listinfo/sundial
Dear All,
I am trying to find examples of sundials
that have been set out on some or all the
faces of a REGULAR OCTAHEDRON.
There are many examples of Dodecahedra
and Icosahedra but I can't find ANY
Octahedra.
If you know of any, please share the
knowledge!!
Very best wishes
Frank
Frank King
Dear All,
Later today, with Martins Gills, I am hosting
a Sundial Zoom Event. Here is the Zoom link:
Invitation...
Frank King - BSS is inviting you to a scheduled Zoom meeting.
Topic: BSS December 2023 Bulletin Follow-up
Time: Jan 24, 2024 17:00 London
Join Zoom Meeting
https
Dear Steve,
Michael, Werner and Fabio have provided some
excellent responses to your question.
If you are ONLY interested in relating three
ANGLES - solar longitude, solar declination
and the obliquity - then this relationship is
indeed all you need:
sin(lambda).sin(obliquity) =
in the engraving
alluding to casting off the old ways and
introducing new ways.
It is worth reading all the writing which is
in very simple French!
Enjoy your day.
Enjoy Year 231.
Frank
Frank King
Cambridge, U.K.
Full instructions for examining the Calendar:
Visit: https://en.wikipedia.org
Dear Michael,
I am most grateful to you for pointing out
an error in my message. I referred to:
> ... your hero Pope Gregory III
and you correctly commented:
> I doubt that he called himself Gregory...
Quite so, BUT you missed a MUCH more serious
error. He was neither Gregory III nor
out.
As others have said: this calendar is
GREAT FUN.
Have a good year!
Frank
Frank King
Cambridge, U.K.
---
https://lists.uni-koeln.de/mailman/listinfo/sundial
Dear Steve,
R. Hooijenga is right. Adding 10 was a common way to proceed.
We are talking about log-to-base-10 which I imagine is rarely used these
days but when it was in common use there were all kinds of tricks. I
suspect these were different in North America from in Europe
Consider the logs
Dear All,
The British Sundial Society is hosting a Zoom event
this coming Saturday 17 April at 16:00 UTC.
[Note 16:00 UTC = 17:00 BST/IST = 18:00 CEST and
= 09:00 PDT = 12:00 EDT etc!]
The outline programme is:
Frank King: Welcome and Introduction
Roger Bailey: French Alpine Sundials
Dear Sara,
It would be good to see a photograph but, from your description, this/these
sound very like the kind of sundial that was almost mass produced in
England in the 1920s. The old dates were not in intended to be fraudulent
but to add an element of quaintness.
Very best wishes
Frank
On
Dear All,
A Happy Leap Year Day to everyone. Should any reader be unfamiliar with my
four-yearly greeting, please look at the sundial list archive for Wed Feb
24 09:11:48 CET 2016 with the Thread Name "Happy Leap Year Day to everyone".
I was delighted, in 2012, to note that not a single
Dear Isabella,
As I expected, there are plenty of list members happy to offer advice. You
have to be a bit circumspect when reading some of it!
Willy Leenders is right to comment unfavourable on the drawing you find at:
http://www.sunclocks.com
The drawing and the wording round it are
uses this mailing list can advise you!
Frank King
Cambridge, U.K.
---
https://lists.uni-koeln.de/mailman/listinfo/sundial
Dear Daniel,
Thank you very much for your excellent explanation. This is exactly what I
was hoping for! Your answer also shows just how useful the Sundial Mailing
List is; we must always thank you for setting it up and for running it.
I enjoy WOZ(G) where G is for Görlitz and this would
Dear Kurt,
Many thanks for your help. I shall try to remember Gmünd as an important
place and, like Greenwich, it begins with 'G' :-)
You have four abbreviations: WOZ, MOZ, MEZ, MESZ
We agree that the English equivalents are LAT, LMT, CET, CEST.
My thesis is that we need two more names for
Dear Jürgen and Kurt,
Thank you both very much for your explanations:
WOZ =A6 Wahre Ortszeit =3D LAT =A6 Local Apparent Time
MOZ =A6 Mittlere Ortszeit =3D LMT =A6 Local Mean Time
My memory must be fading=21 I had forgotten Ortszeit and,
now, I remember that Reinhold Kriegler explained
you help me with MOZ?
I guessed Mittel Ost Zeit but this doesn't seem to exist!!
Very best wishes
Frank
Frank King
Cambridge, U.K.
On Tue, 26 Nov 2019 at 20:48, wrote:
> Dear Sundialists,
>
>
>
> there has been some progress within the latest months. You are invited to
>
ANT
Teaching geometry in schools seems to have gone out of fashion in most of
the world. In my day, we were taught how to calculate conic sections at 16
years old.
Very best wishes
Frank
Frank King
Cambridge, U.K.
---
https://lists.uni-koeln.de/mail
or DE406, etc..) that could be different from
> JPL and IMCCE. This does not mean that one is better than the other one.
>
> I have not investigated Sol et Umbra yet, because of lack of time, but
> this could come from the selected location not being the center of the
> Earth.
>
>
>
Dear Hervé,
Congratulations on your comments on my
puzzle about the September Equinox last
month...
> It seems that the answer to your question
> can be found in the attached picture
> inclosed in a recent information letter
> issued by the French IMCCE institute
> specialised in celestial
the advice given in:
https://lists.uni-koeln.de/mailman/listinfo/sundial
Here it still says that the limit is 50kB and that is definitely too small!
Very best wishes
Frank
Frank King
Cambridge, U.K.
---
https://lists.uni-koeln.de/mailman
Dear Fabio,
Yes, in England, there are some very unusual
traditions at the start of summer each year!
Ciao Frank
---
https://lists.uni-koeln.de/mailman/listinfo/sundial
to change the clock on an oven. I
managed to set the timer to cook for an hour but changing the main clock
defeated me.
Frank King
Cambridge, U.K.
---
https://lists.uni-koeln.de/mailman/listinfo/sundial
Dear Fabio,
This is very sad news indeed. I was in correspondence with Gianni only a
few months ago. I learnt a huge amount about sundials from him over the
past 20 years. His book about Islamic sundials is a masterpiece. We shall
miss him very much.
Frank
Frank King
Cambridge, U.K
dimenticherò.
Lux perpetua luceat eis
Frank
Frank King
Cambridge, U.K.
---
https://lists.uni-koeln.de/mailman/listinfo/sundial
Dear Fabio,
Many thanks for your follow-up. I look forward to hearing more when you
get your book back.
I wonder how many people know how difficult it is to define 'Sunday'!!
It is possible to define Sunday so that, sometimes, half the planet has
Easter after one full moon and the other half
Dear Fabio,
I think the Spencer-Jones algorithm is
now widely accepted as defining when
Easter will be observed (by both the
Roman Catholic Church and the Anglican
Church for the foreseeable future).
What is interesting is just how often
it produces the same date as the naive
rule of 'the first
Dear Roger,
I note that you say:
> My reference on this topic is The Sun in
> the Church by J L Heilbron.
He is pretty sound on this and, as early
as page 3, notes that the time of the
equinox and the time of full moon depend
where you are on the planet. He adds,
"as, of course does Sunday".
ion is one of the greatest gnomonic inventions.
You don't have to have the zenith in the centre. On astrolabes, the centre
is a projection of the north celestial pole.
Frank
Frank King
Cambridge, U.K.
---
https://lists.uni-koeln.de/mailman/listinfo/sundial
last year and you
can see:
1. There is no nodus.
2. The surrounding circle is the
projection of the horizon so
you can see the WHOLE heliodrome.
I think I shall use this word more
frequently!
Frank
Frank King
Cambridge, U.K.
---
https
eliodromo highlighted?
Frank
Frank King
Cambridge, U.K.
---
https://lists.uni-koeln.de/mailman/listinfo/sundial
is more challenging!
In English, this translates literally as
"eye-cap" which I think of as something
for medical use, for washing your eyes.
I rather suspect that the French also use
this to mean aperture nodus but I should
like confirmation.
Frank
Frank King
Cambridge, U.K.
--
>From where I am sitting:
My longitude offset (from the
Greenwich meridian) is one-eighth
of a degree east or 30 seconds of
time.
'Offset' is used for angles, time
or distance.
Frank
Frank King
Cambridge, U.K.
---
https://lists.uni
seem very
nicely made.
Frank
Frank King
Cambridge, U.K.
---
https://lists.uni-koeln.de/mailman/listinfo/sundial
Dear Willy et al,
My suspicions ares confirmed...
I have just received a message from David Leafe:
Unfortunately, although I sent them the revised
scientific information as we agreed it, they had
to cut it down and I'm not sure that it now all
makes sense...
The errors are NOT the fault of
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
Dear John,
Many thanks for your seal of approval...
> Bravo - two quarters of a double horizontal dial!
A fair summary, but note that it doesn't suffer from
the knife-edge gnomon bug that most double horizontal
dials suffer from. Fancy going wrong at noon of all
times of day. Grrr!
The
Dear Alastair,
Many thanks for your kind words...
> Your design is wonderful...
I hope you enjoy the book.
You ask...
> ... have you come across the term 'azimuth
> circles', how would you define this term?
I have heard this term in several contexts.
In an astronomical context, any great
Dear All,
I have a simple rule with my puzzles: wait for a reply from Geoff Thurston and
then reveal all. The time has come!
In the recent spate of messages, both Bill Gottesman and Steve Lelievre were
very close. Bill is the only person to suggest an azimuthal dial with
vertical styles
Dear Maciej and Sara,
Gosh. Those are really incredible dials.
The Nested L-shapes of the chapter rings
on the Jacques Le Marie dial are very
cleverly set out. I wonder how big a
market there was for this kind of dial!
Maciej's description of a Nuremberg
Diptych - The shadow was cast by the
Dear Maciej, John and Steve
Congratulations on coming up with several
ideas. I should have asked your advice
several months ago!
Although your ideas seem wildly different,
they all share elements of the actual design
which I shall reveal in due course.
Maciej: I am most grateful to you for
DIAL FITS INSIDE THE GNOMON GAP
Question 1: What does the design look like?
Question 2: Can this possibly look good?
Question 3: What is the 'unusual space'?
A Happy New Year to you all.
Frank King
Cambridge, U.K.
---
https://lists.uni-koeln.de
Dear Steve,
Your subject line is ambiguous...
EU backs ending Daylight Saving Time
Does this mean:
A: The EU wants to give up DST?
or:
B: The EU wants DST not to end?
The report suggests the latter:
Commission President Jean-Claude Juncker
said millions "believe that in future,
Dear Bill,
Sunclocks are genuine. Some people are very
enthusiastic about them, others are not. You
have almost certainly seen a Sunclocks dial
without realising it.
They have an interesting business model...
If you want a sundial you are given several
options:
1. Buy a full set of
Dear Doug,
On Tuesday 22 May you wrote:
> I regard a subject line as a
> simple courtesy!
As Fred noted, the irony is that
your own message didn't include a
subject line. I endorse Fred's
suggestion that you should study
Steve Lelievre's note.
I would add a personal plea not
to go in for
Dear All,
Rest assured that our Queen is well advised...
If she wants to discuss trees, she
brings in Sir David Attenborough.
If she wants her sundial moved, she
consults me.
This sundial has been moved before. Its
most recent location was fine when it was
placed there
Dear Reinhold,
Yes, let us all join the party on
Asteroid 315046 and celebrate the
birthday of the greatest living
diallist.
Happy Birthday Gianni
Frank King
Cambridge, U.K.
---
https://lists.uni-koeln.de/mailman/listinfo/sundial
Dear Rolf,
Many thanks for that diagram. It makes
everything very clear.
Where I live, at 52N, there is very little
change in the width of the shadow of a rod
gnomon over the course of the day. Almost
no one notices it.
In the tropics, the change is much more
obvious.
You can see why I chose
Dear Geoff and John,
> Surely Geoff Thurston is right?
Yes. He is!
You don't even need to think in three
dimensions. The edges of the shadow
must run to the base of the gnomon
and must touch tangentially.
The base is indeed an ellipse. The
contact points are always opposite
one another (by
Dear John,
A moot point...
> ... why should any sane normal
> person want to help Trump...
Ah. I was thinking in terms of
"displacement therapy".
Thinking about sundials must be
better for one's mental health
than drinking copious quantities
of Diet Coke?
Just trying to be helpful :-)
Frank
Dear All,
I gather from the UK media that
the recent medical check-up
undertaken by the U.S. President
involved some "cognitive tests"
and he scored 30 out of 30.
One of these tests requires the
subject to mark in the hands of
a clock at a specified time.
It is, of course, reassuring to
know
Dear Brad,
I'm delighted that you enjoyued
my "tutorial"...
> However, its your step 19 I am
> interested in.
Ah yes. That's where I mention
marking out equal hours. I thought
you would be most interested in
that step :-)
You add...
> And if I do tilt the hemispherium
> so that the horizon
Dear Brad,
You say:
> I am looking to make a
> hemicyclium-type sundial
> (half-hemisphere) in a
> metal working class.
> Am I missing anything?
Er, yes. Rather a lot alas...
Before you start bashing metal
it may be worth spending rather
less effort on a prototype.
> ...they are
Dear Geoff,
Many congratulations on your proof...
When I set the puzzle, I thought three things:
1. I am really setting this for Geoff to solve.
2. He will certainly solve it and will probably
be the first to publish.
3. His proof will either match mine or be more
elegant.
I was
Dear All,
Referring to the Golden Ratio and Sundials, Donald
Snyder wrote:
I see nothing obvious except ... trivial
possibilities.
Try Googling Dodecahedral Sundial and you will
see many examples. Here is one chosen at random:
at a time.
Frank King
Cambridge, U.K.
---
https://lists.uni-koeln.de/mailman/listinfo/sundial
Dear Steve,
Part 2 of your enquiry asserted that...
...throughout the 19th century...
the French railways system used
heliochronometers installed at each
station for daily calibration of station
clocks?
Again, this is a good story but I simply
cannot see why this would be
Dear Steve,
I have read the replies to your enquiry and I
am not yet convinced by the responses to either
Part 1 or Part 2!
I'll restrict myself to Part 1, where it is
asserted...
...that Louis XIV issued some kind of edict
that all clocks manufactured in France were
to be Equation
Dear Doug,
The answers to your first question about
noting seasonal drift 1000 years ago have
all missed something crucial...
The astronomical comments have been very
sound but what is missing is any account
of just how you would maintain your
records?
These days you could buy a desk-top diary
Dear Roger,
Thank you for your comments on the John Dee
implementation of the Omar Khayyam calendar.
> At one longitude, 77° W, the equinox
> would always be on the same day. Is this
> God's Longitude?
Yes. At that longitude the vernal equinox
would invariably fall on 21 March.
Sadly, this
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Dear Geoff,
As so often, you cause me to reflect a
little and to refine my analysis...
> I wonder if the errors might be masked
> by the 32 arc minute solar penumbra.
In pondering this "instrument" I made
the naive assumption
Dear John,
I am not sure the Chief Engineer fully
grasped what is going on though he has
indeed appreciated that, at the required
moment, both the altitude and the azimuth
of the sun change from one year to the
the next.
In a crucial sentence he asserts:
Each year, the center of the sun is
t the result is that we
are lumbered with an unhelpful calendar which
is, I suppose, upward-compatible with its
predecessor.
I share the view that "upward-compatibility is
the business of deliberately not putting right
someone else's mistakes".
Many apologies. Another rant I fear!
Very best wishes
Frank
Frank King
Cambridge, U.K.
---
https://lists.uni-koeln.de/mailman/listinfo/sundial
Dear All,
Many interesting comments...
David Brown wrote:
> ...the place where you add/remove the coins
> is below the current C.G.
This is a theoretical possibility but all
the large pendulum clocks I have looked
at have an annular tray round the shaft
ABOVE the pendulum bob...
There are
Dear All,
The voting pattern has swung away from
1.5s to 0.5s and we shall see whether
this trend continues!
There is an embellishment to Mike Shaw's
comment:
The radio clock stopped for 1 second
at midnight
This isn't quite what happens. Indeed,
there seems not to be a general pattern.
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
Dear Roger,
Delighted to see that you heed my Rule 2:
2. Never believe anything you read
anywhere [else] without checking.
Very properly you have checked my assertions
and found them wanting! That's the kind of
guy I like!
I was basing my false assertions on a report
from an erstwhile
Dear Frans,
I was interested and amused by your comments
on the Delhi sundial...
> According to the newspaper article...
Huh! I live by two simple rules:
1. Never believe anything you read in
Newspapers without checking.
2. Never believe anything you read
anywhere else without
Dear Beverley,
You ask:
> Do the members of this list know,
> whether there are some (or even ANY)
> sundial designers in INDIA...
There are several modern sundials in India
so someone must be designing them! I have
even had a hand in a dial in Goa [do you
count that as India?] myself.
To
Dear John,
You are right to point out the error
of Doug's ways. I have been known to
do this myself :-)
That said, this isn't quite right
either...
> It is only the benighted people who
> are forced to live in the northern
> hemisphere who persist with the
> belief of a southerly sun.
I have
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
Dear Doug,
I read your message and your attachment.
There are so many flaws in your analysis
that it is difficult to know where to
begin.
Since you find road accident statistics
so compelling I shall confine myself to
demolishing all you have to say there...
There is a wonderful book by
Dear John,
You reply...
> I have to take issue with your notion
> that God ... handed us a 24 hour clock.
I suggest you read my message a little
more carefully.
a) I didn't mention God at all.
b) I was exceptionally careful to
spell out that the 24-hour clock
was irrelevant.
I was
ff one end of a
blanket and stitching it on to the other
end you get a longer blanket.
Frank King
Cambridge, U.K.
---
https://lists.uni-koeln.de/mailman/listinfo/sundial
Dear Rolf,
Yes, this is indeed the answer that I was
hoping for:
The midpoints M1 and M2 of parallel chords
lie on a (conjugate) diameter. And its
midpoint M is the centre of the ellipse.
The proof is trivial. You just have to
consider what the figure looks like if
you project the
Kevin Karney wrote:
Oops - misread for Mike Cowan
Ah, much better.
Now try Mike Cowham and you will
neatly illustrate the meaning of
Third Time Lucky :-)
Frank
---
https://lists.uni-koeln.de/mailman/listinfo/sundial
Kevin Karney wrote:
Dennis,
Your nearest port of call would be the
geology department at the Sedgwick museum
in Cambridge...
Many readers will find this a little puzzling
given that Dennis lives but a stone's throw
from The Cockburn Geological Museum at the
University of Edinburgh whereas
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
Dear Andrew,
You are quite right...
> I thought that you were looking for a
> "straight-edge" and compass construction
> on the sheet of paper.
Yes. I was!
Don Snyder gave us pointers to what I was
hoping for...
> first find the ellipse center
>
>
Dear Rudolph,
Glad you enjoyed the puzzle or, at least,
the solution...
> Brilliant!
You add...
> I never realized that the distance from
> the focus to the end of the minor axis
> equals the half major axis...
Have you never tried drawing an ellipse
with a Length of String and Two Pins?
Dear Dave and Donald,
This puzzle actually has serious
practical sundial applications
as I shall illustrate. First:
Good try Dave...
> Personally, I'd fold the paper,
> superimposing the reflected
> half-ellipse, crease it, unfold,
> rotate ~90 degrees and repeat!
Although this is not what I
Dear Geoff,
I had a private list of people I
expected to respond and I have been
waiting for your answer!
> I think that these instructions might
> work if you ventured to the antarctic
> circle during the southern winter and
> then trecked to a position such that
> your latitude is greater than
anet would you have to
be, and at what time of year, for these
instructions to give the correct result?
Moral:
It is better to learn from other people's
mistakes than from your own.
Frank King
Cambridge, U.K.
P.S. The home page of the website is:
http://wiki.dtonline.org
ore
> a sundial hat to the Ascot Races
> back in 2009.
Yes, a truly stunning hat!
Mike Shaw added:
> Note Lord White with compass in hand
He is still "Sir George White" as far
as I know?
Frank King
Cambridge, U.K.
---
Dear All,
I add my congratulations to Roger Bailey
and note that he generously refers to my
article on "Sundials and Leap Years" in
the BSS Bulletin of December 2011.
Bob Kellogg referred to this in one of his
excellent "Sundials for Starters" pieces:
"Bisextile Years and the Analemma" in the
Dear John,
At last! Congratulations! You go to
the top of the class and put all those
youngsters to shame!!
> ... a north-facing wall on the
> Arctic Circle at the summer
> solstice, or a south-facing wall
> on the Antarctic circle at the
> summer solstice down under.
The analysis is easy...
Dear Willy and Geoff,
Good answers but the correct value
exceeds both your scores.
Let's see who else will rise to the
challenge before I declare my hand!
Frank
---
https://lists.uni-koeln.de/mailman/listinfo/sundial
shine on a vertical wall?
You can choose the latitude and you
can choose the orientation of the
wall and you can choose the solar
declination.
Frank King
Cambridge, U.K.
---
https://lists.uni-koeln.de/mailman/listinfo/sundial
at they do not indulge in the
dumbing-down from which we in the U.K. seem
to suffer.
Frank King
Cambridge, U.K.
---
https://lists.uni-koeln.de/mailman/listinfo/sundial
ight.
In short, the bite taken out of
Mount Baker has nothing to do with
diffraction, refraction or the
atmosphere (or lack of it) on the
mountain.
Frank King
Cambridge, U.K.
---
https://lists.uni-koeln.de/mailman/listinfo/sundial
by Huygens and Fresnel.
I should be interested to hear whether
this is right. Should one expect a
slight change in colour between the sun
ABOVE the bite and IN the bite?
Very best wishes
Frank
Frank King
Cambridge, U.K.
---
https://lists.uni-koeln.
for
164-year-old stonework.
I have asked for the name of the
property and who owned it in 1850
but I have not had an answer!
Frank King
Cambridge, U.K.
---
https://lists.uni-koeln.de/mailman/listinfo/sundial
extensive
European coverage too.
Have fun!
Frank King
---
https://lists.uni-koeln.de/mailman/listinfo/sundial
Day is really
24 February but there are probably only
two other people on this list who agree
with that assertion!
[I distinguish here between the extra
DAY and the extra DATE in a leap year.]
Very best wishes,
Frank
Frank King
Cambridge, U.K
Dear Doug,
You say...
Not the only problem in this area!
I rather fancy they should go back to
having a resident aggressive Astronomer
Royal; someone like Nevil Maskelyne
would do. He would crack the whip
over all these surveyors and give them
the choice of putting their work right
or being
Dear All,
Here is a cautionary tale. In summary:
NEVER believe ANYTHING without checking!
A little while ago, Doug Bateman mentioned
that there were some lines of longitude
marked in the paving of Peninsula Square
by the O2 Arena in London. You can see
these as follows...
Enter Google Maps
Dear Geoff,
Given that you have checked the Ordnance
Survey's A guide to coordinate systems in
Great Britain you will know everything
that I know on this and, no doubt, much
more besides.
What I didn't quite deduce from the document
is how individual features get into the
grid squares! You
Dear Geoff,
I share your lament...
I thought that I understood the principles
of the OSGB but since Keith said that it is
not strictly based on a transverse Mercator
projection, I am now confused again.
Well, the Ordnance Survey certainly WAS based
on a transverse Mercator projection, and
Dear Tony,
What a fun thread you have spawned!
Mercator is possibly the most famous
Belgian, not that Belgium existed in
his day but let's overlook that detail.
The mathematics of Mercator's projection
is quite challenging. Certainly Mercator
himself didn't understand it!
The first proper
1 - 100 of 410 matches
Mail list logo
