English language summaries of =De Zonnewijzerkring= journal

[Rudolf Hooijenga]

Hello fellow dialists,

for those of you who have difficulty deciphering Dutch and want to know if
that's bad or okay, I have started (last year) to make English language
summaries of our journal.
For what it's worth, I made a web page where you can find them. Nope, the
newest one has not been done yet. As they say, that will happen soon
(mañana).

When I understand enough of this HTML business, perhaps I'll even add
pictures.

Have fun with my version of English! As always, pointers (or dictionaries)
welcome.

Rudolf (Ruud) Hooijenga

http://www.rhayward.demon.nl

New Summary of De Zonnewijzerkring bulletin

[Rudolf Hooijenga]

Dear fellow gnomonists,
 
I am happy to inform you that the new summary, 
99-2, is on my homepage.
It even has some pictures in it. Please have a 
look and enjoy our Bulletin even more!
 

Homepage:
http://www.rhayward.demon.nl
 
Rudolf Hooijenga
[EMAIL PROTECTED]
[EMAIL PROTECTED]
 

Setting X-Y sizes of Excel plots

[Rudolf Hooijenga]

Dear All On The List,
 
In Microsoft's Excel I can easily plot X-Y pairs, 
so that I can lay out, for example, an analemmic dial.
By fiddling with the mouse I can stretch the graph 
until it looks about right. See attachement (5 kB, hope that's ok).
 
It would be nice, though, if I could just input the 
wanted sizes in centimeters (or inches), just like you can for a figure in Word 
for instance.
 
What does work is this: I copy the graph, then 
paste it in Word, then choose Edit Figure and just input the wanted sizes. It 
will then print fairly squarish (if it should be square..)
I cannot find such an input possibility in Excel 
itself. Am I overlooking something?
 
If I'm not, I'll just import in Word, no problem. 
Just curious.
Thank you for bearing with me!
Kind regards,
 
Ruud
[EMAIL PROTECTED]
[EMAIL PROTECTED]

Setting X-Y sizes of Excel plots

[Rudolf Hooijenga]

Ops... forgot the attachment.
This is what I meant.
It looks about allright, but can I specify the X and Y axis lengths?
Regards,
Rudolf
 

Attachment converted: MAC Hard Disk:ana.gif (GIFf/JVWR) (0001A3BB)

Re: A dial by any other name...

[Rudolf Hooijenga]

Hello all,

I don't know if I have asked this before, but anyway, Tony made me think of
it again.
Is there anywhere available a word list for sundial topics?
The usual Internet search engines are less efficient for this one, for lack
of throughput?

What I need most (for my English-language summaries of the Dutch Bulletins)
is a list containing at least the English expressions for various parts of
diverse kinds of sundials, especially of course the uncommon ones...
It does not even have to contain translations, as I'm a very good guesser.
:-)

Especially for the more esoteric designs, my own paper dictionary is at a
complete loss.
Rudolf (Ruud) Hooijenga
[EMAIL PROTECTED]
[EMAIL PROTECTED]




- Original Message -
From: Tony Moss <[EMAIL PROTECTED]>
To: Sundial Mail List 
Sent: Wednesday, September 01, 1999 11:48 AM
Subject: A dial by any other namethe response.


Fellow Shadow Watchers.

Some time ago I requested List members to send me the word/s for 'sundial'
in as many languages as possible with the promise that I would publish the
result via the List when complete - I was unaware of the list already
prepared by Daniel Roth at the time.

(...)

Re: A dial by any other name...

[Rudolf Hooijenga]

Thank you ever so much Frederick,
this is just the thing to ask my wife for my birthday! She never knows what
to get me.. ;-)
Seems this book will contain the solution to every language problem I will
ever run in to in the future!
Again, thanks for the tip.

Rudolf


- Original Message -
From: Frederick W. Sawyer III <[EMAIL PROTECTED]>
To: Rudolf Hooijenga <[EMAIL PROTECTED]>
Sent: Thursday, September 02, 1999 12:32 AM
Subject: Re: A dial by any other name...


Rudolf,

The following notice appears in the current issue of The Compendium.  It
may be what you are looking for:

Gnomonic Octolingual Vocabulary, (2nd ed.) by Josep Maria Vallhonrat
(..)

Re: Setting X-Y sizes of Excel plots

[Rudolf Hooijenga]

Thank you Lufkin,
it's a pity one cannot do it, but your information saves me a lot of time
looking!

Rudolf

- Original Message -
> Unfortunately, there is no way to control the size of Excel graphs other
> than with the mouse.  Even Visual Basic for Applications (which allows
> almost total programmatic control of an Excel workbook) does not permit
> this.

Re: Formula to calculate sunrise

[Rudolf Hooijenga]

> - Original Message -
 > From: Roger Bailey <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>; 
> Sent: Saturday, September 11, 1999 6:50 PM
> Subject: Re: Formula to calculate sunrise

> The easy, elegant formulae that you can use to determine sun rise and set
> phenomena are:
>
> Sunrise time t:   Cos t = Tan L x Tan D
> Sunrise location: Cos Z = Sin D / Cos L
> Sunrise Path: Cos psi = Sin l / Cos D


About a year and a half ago, someone suggested this formula (the top one)
should be on a T-shirt.
I cannot look up who it was, as that mail is on a computer at my former
employer (don't worry, got a better job).

Well, I actually had a T shirt made, with a picture of a sunset on it, and
that very formula.

Lay people look startled when they see it; dialists grin and nod.

It's a little like the Scottish eleven-forty-two cannon, a little like a
noon cannon except it fires at eleven fortytwo. Tourist leap in the air, but
locals grin and nod- that's how they keep them apart.



Argh! I have been sending HTML mail all this time! It came with the mail
program but I never read the manual.
I have switched it off now.



May your shadows be always to the point.
Rudolf

Loy Chun box dial

[Rudolf Hooijenga]

Hello Loy,
well, I am sure you know all about large attachments now..

In the debate, we forgot to say HELLO and WELCOME to you. Of course everyone
wishes you good luck in your new career.
I like the idea of the box dial, by the way.

Rudolf Hooijenga
[EMAIL PROTECTED] (home)
[EMAIL PROTECTED] (office)


>Dear shade-infatuated friends
>I'm a new commer for North America from Thailand.
>I just finished a new programe to design a box
>sunclock--project on 4 sides. For initiation, I
>made one for my new city, new country--Toronto,
>Ontario, Canada.

Summary of special bulletin 99.3

[Rudolf Hooijenga]

Hello fellow dialists,

I have placed a summary of Bulletin 99.3 of De Zonnewijzerkring on my web
page.
This special bulletin consists of a paper on Greek conical sundials, and a
recapitulative supplement on "Sundials in The Netherlands".
I will translate the entire Jan Kragten paper later. However, amateur that I
am, I have to divide my time between several issues.. it will be a while.


Rudolf Hooijenga
[EMAIL PROTECTED] (home)
[EMAIL PROTECTED] (office)

Re: Equation of Time Graph wrong way up Down Under ?

[Rudolf Hooijenga]

The "Australian way", which is also what Fraçois Blateyron does, can be
regarded as giving the correction to sundial time to find mean time.

While that in itself is commendable, I really like more the presentation
which has the EOT negative in February and positive in November, because the
dial is really slow in February and really fast in November, which is
represented by the wavy EOT line, whereas Mean Time has always equal-length
seconds, and days, and is best represented by the straight horizontal line
of zero.

If you then add "Sundial Slow" on the February (-) side, and "Sundial Fast"
on the November (+) side, I think the users and passers-by will have no
difficulty interpreting the meaning.

If this is also the "Astronomical" way of doing it (and it is), so much the
better :-)

Rudolf Hooijenga
[EMAIL PROTECTED] (home)
[EMAIL PROTECTED] (office)



- Original Message -
From: John Hall <[EMAIL PROTECTED]>
To: 
Sent: Friday, September 24, 1999 4:22 AM
Subject: Equation of Time Graph wrong way up Down Under ?


> Can somebody please shed light on a problem I have encountered with the
> standard graph of the Equation of Time.
>
> I have used the routines by Fer de Vries to generate the graph and the
print
> outs check out perfectly with all standard references. They all indicate
> that at this time of the year the correction for the EQT is around +(plus)
> 7m 42sec - I checked this with the Luke Coletti web site this morning ;-)
>
> Now the problem is that all Australian printed references I have checked
> suggest that this figure should be - (minus) 7m 42sec. My understanding is
> that the EQT is the EQT irrespective of our position on the globe.

Fw: Equation of Time Graph wrong way up Down Under ?

[Rudolf Hooijenga]

- Original Message -
From: Krzysztof Kotynia <[EMAIL PROTECTED]>
To: Rudolf Hooijenga <[EMAIL PROTECTED]>
Sent: Saturday, September 25, 1999 11:34 AM
Subject: Re: Equation of Time Graph wrong way up Down Under ?


> > While that in itself is commendable, I really like more the presentation
> > which has the EOT negative in February and positive in November, because
the
> > dial is really slow in February and really fast in November, which is
> > represented by the wavy EOT line, whereas Mean Time has always
equal-length
> > seconds, and days, and is best represented by the straight horizontal
line
> > of zero.
> >
> In 1930 International Astronomical Union agreed for
> eq. of time to take role of an instrumental correction
> to receive true (or apparent) time from the mean time
> shown by clocks,
> similarly to e.g. corrections added
> to sextant measurements  to receive true altitude  of  the
> sun from instrumental measurements.
>
> So the equation of time should  be taken with a minus sign
> as a correction for sundial to receive a mean time.
>
>
>
>
> Best regards
> Krzysztof Kotynia
>

Tyro?

[Rudolf Hooijenga]

This is one for my private word list:
what is a "Tyro" ? Of course I understand the meaning from this sentence,
but where does the word come from?

--
> It could be worthwhile having a short section on what to look out for,
> and what to avoid, if a tyro is thinking of purchasing one of the
> cheap mass produced dials often on sale in garden stores.
>
> Les Cowley

Re: Ah hah! (?)

[Rudolf Hooijenga]

Could not the EOT have always been detected by comparing observations on
stars with solar time? Astronomers would know about the 366 vs. 365 days per
year, but would notice slight variations about even that - the EOT.
I would be surprised if, say, Hipparchus had not know its value.

- Original Message -
From: Tom McHugh <[EMAIL PROTECTED]>
To: Ryan Weh <[EMAIL PROTECTED]>; 
Sent: Wednesday, November 17, 1999 9:22 AM
Subject: Re: Ah hah! (?)


(...)
I suspect, though, that as soon as the elliptical nature of the
earth's orbit was established, that it was quickly realized that
there would be an EOT variation, even though clocks may not have
been accurate enough to show it.  I do not know if there was a
mathematical discovery of EOT predating accurate clocks.
(...)

Re: Sundial Mail List Archive

[Rudolf Hooijenga]

This is amazingly interesting stuff! It carries archives of lots of other
lists that are likely to interest us as well. Thank you for the pointer!

By the way, I noted you can also use the address:

www.astroarchive.com

Rudolf

- Original Message -
From: Mac Oglesby <[EMAIL PROTECTED]>
> The current archive for the Sundial Mail List (and lots of other lists)
is:
> http://194.230.53.250
>

Re: Analemma Stuff

[Rudolf Hooijenga]

>From William Lee Kennon, "Astronomy":

-quote-
The actual values of the equation of time from day to day throughout the
year will depend on the point where the real sun and the fictitious sun are
made to coincide in right ascension. It is desirable that this point be so
chosen that the values of the equation of time throughout the year will be
distributed as symmetrically as may be with respect to the corresponding
values of mean solar time. The proper mathematical analysis shows that this
will be accomplished when the fictitious sun is made to coincide with the
real sun when the latter is at perihelion. (This occurs about January 1.)
-unquote

While it is true that the paths of the real and the fictitious sun share the
first of Aries, the suns do not get there at the same time; there is a
difference of about 7 minutes in their hour angles. Does that help or make
it worse?

Rudolf


- Original Message -
From: Daniel Lee Wenger <[EMAIL PROTECTED]>
To: Luke Coletti <[EMAIL PROTECTED]>

> Luke
>
> Your argument is very clear as usual, but it is the statement that by
> definition the mean sun
> and the dynamical mean sun coincide at the Vernal Equinox that is the key
> to the question.

Re: Gnomon for Vertical Decliner

[Rudolf Hooijenga]

Bill,

I would certainly like to have a look at it, but don't normally have access
to the Compendium. Can I find a picture of it somewhere on the net?
Thank you very much,

Rudolf Hooijenga
[EMAIL PROTECTED]

- Original Message -
From: <[EMAIL PROTECTED]>
(...)
> On page 30 of the NASS Compendium for September 2000 there is a
diagram
> of a self similar rosette pattern.  If this pattern is reduced to an
> appropriate size (say 1 inch diameter) onto transparent plastic and
mounted,
> with its plane parallel to the sundial surface, at the point where the
nodus
> would ordinarily be, it will serve the purpose of a nodus. Surprisingly,
the
> shadow it makes will be equally sharp and well defined regardless of the
> distance to the dial plate.
(...)

Round things give round shadows

[Rudolf Hooijenga]

Hello sun worshippers,

Another example of the "round shape on the dial face no matter what the
time"
discussion:

Almost all of the sundials in the Deutsches Museum "Sundial garden" have
circular disks on top of their gnomons.
The disks are parallel to the face on which their shadow is read, and yes,
their shadows are always round. It is fairly easy to estimate the middle.

As an added benefit, especially in public places such as this: the gnomon
tip is not easily deformed this way, and what may be more important, the
same holds for people bumping into them.

I hope the two attached pictures are of some use. One is the polyeder
sundial, the other is an inclining and reclining dial with babylonian and
italian lines.

Rudolf




Attachment converted: Macintosh HD:bab-ital.jpg (JPEG/JVWR) (0001F2E2)
Attachment converted: Macintosh HD:polyeder.jpg (JPEG/JVWR) (0001F2E3)

Summary of Dutch Sundial Society Bulletin 00.3

[Rudolf Hooijenga]

Hello fellow sungazers,

I have just put an English-language summary of Bulletin 00.3 on my homepage.
To make it more interesting, I added some of the pictures. Hopefully it does
not slow down your connection too much.

Feel free to have a look on

http://www.rhayward.demon.nl/

also, if you encounter any broken links, could you please let me know- I
have been moving some files around..

Regards,
Rudolf

Re: Summary of Dutch Sundial Society Bulletin 00.3

[Rudolf Hooijenga]

Hi Dave and all other readers,
Thank you for the kind responses.

Actually, the numbers are just the page numbers of the original paper
bulletin. This makes for easy reference.
The summary covers all the articles in the Bulletin.
You may note that my summary is always one issue of the Bulletin behind,
though.

Have a good New Year!
Rudolf

- Original Message -
From: Dave Bell <[EMAIL PROTECTED]>
>
>   I saw with interest the point at section 27:

Broken Summary link repaired

[Rudolf Hooijenga]

Hello good sunwatchers,

As Fer kindly pointed out to me, the link to the new Bulletin 99.4 summary
did not work.

As far as I can tell I have fixed it (which is not all that easy from a
hotel room at hotel telephone rates ;-)  ), at least, even after purging the
cache, the summary page will now download to my browser. Let's hope Windows
is not pulling my other leg now..

Sorry for the cockup.
Gee, the sun stays low here in Oslo.

Rudolf

Spare time in Oslo, Norway!

[Rudolf Hooijenga]

Hello All-on-the-List,

to my surprise, I find I will be almost a week longer in Oslo than I had
anticipated. This does mean that I wish I had prepared for the trip rather
better than I have, dialwise speaking.

And so.. the obvious question.. Where does one go dial-hunting in or around
Oslo these days?

Mind you, we DO have sun. It's low altitude, but it _is_ real sun, with
shadows and all.

Grateful,
Rudolf
59.55N 10.45E

Re: Rules of thumb

[Rudolf Hooijenga]

The "true" sunrise happens when you can already see the sun. At "true"
sunset, you can still see the sun. (assuming other conditions to be
helpful).
Under "normal" circumstances, the lower limb of the sun will be seen about
2/3 of a sun's diameter above the horizon at the times of astronomical
sunrise or sunset.

On board ship, we called this the "Dachshund Rule".  You could check a
compass with the azimuth of the sun when a small dog could just pass under
it. That would be the time of astronomical sunset/rise which you could look
up in the Nautical Almanac.

Rudolf

Better late than never: summary of B99.4

[Rudolf Hooijenga]

Sundial lovers,
 
for a time now I had the summary of De 
Zonnewijzerkring Bulletin 99.4 ready. Only now did it occur to me that you might 
want it on my web page.
I have taken the liberty to put a new picture of 
myself on it, standing next to a Berhardt sundial.
Also a photo of our local scarecrow in action on 
the airfield.
 
I will be in Oslo for the next two weeks, but with 
luck, I will still read my email.
Good luck!
 

Amazingly good book on Astronavigation

[Rudolf Hooijenga]

For those of you who read German (wow, the load on 
the Net seems a lot lighter now?):-
 
This is a book that will really tell you how to 
read a sextant and how to use the Almanac or your pc or calculator to fix your 
position. It even includes some Almanac pages so you can work the 
exercises.
It is very clearly written, and I vastly enjoyed 
it. For less than 20 DM (11 dollars US) you cannot go wrong.
 
Needless to say, the information is extremely 
useful in dialing problems as well. 
Hey, it is really the same stuff, only done 
backwards!
 
Stein, Walter:
Astronomische Navigation / Walter Stein; Werner 
Kumm. -
10., aktualisierte Aufl. - Bielefeld: Klasing, 
1997
(Yacht-Bücherei; Bd. 88)
ISBN 3-87412-0138-0
 
Enjoy.

Attachment converted: Macintosh HD:kugel2.gif (GIFf/JVWR) (CFBA)

Fw: laser engraving on stone

[Rudolf Hooijenga]

When I wanted to make a sundial for my mother-in-law, I had a nice slab
polished and the tombstone maker glued a kind of sandblast resistant rubber
on it. The polishing was done so smoothly that the rubber held well, but it
would not have shown a shadow at all well.

I then drew the artwork on the rubber and my wife (who uses knives in a
safer way than I do) cut the design with an Xacto-style knife.
We then returned the slab to the tombstone maker who sandblasted the slab to
the right depth, removed the rubber, and cleaned the stone.

Then he removed the very smooth finish from the surface and made it into a
surface that shows the shadow much better. (presumably by lightly blasting
the whole slab again? )
The whole affair cost only little more than the slab itself.

This seems practical in any country.

Count only the sunny hours,
Rudolf

- Original Message -
From: John Carmichael <[EMAIL PROTECTED]>
To: 
Sent: Wednesday, March 08, 2000 4:07 PM
Subject: laser engraving on stone


> Hello dialmakers:
>
> The past few years, the local garden centers have been selling rounded
> smooth river rock that have single supposedly inspiring  words engraved on
> each one (Like "Light" or "imagine" for example). The quality of engraving
> is good, much like tombstone engraving.  The manager told me that they
were
> engraved by laser.  Tombstones are also engraved by laser, I've been told.
>
> I don't know how thin the lines can be done or if there is any control
over
> cutting depth.
> I once asked the local tombstone maker if I brought him a drawing of a
> sundial could he have it laser engraved?  He said sure, for 600.00
dollars!
> I thanked him and left.
>
> John Carmichael
>
> p.s.  I'll be on vacation till Monday, so won't answer e-mails till
Tuesday.
>
>

Is this a sundial?

[Rudolf Hooijenga]

Hello all,

A 12K picture is attached, I hope that's OK.
My parents visited Israel last year. A guide thought it was some sort of
sundial so my mother took this photo for me.
If it is, I sure don't know how it worked. If it isn't, what could it be?
Any thoughts out there?

Rudolf



Attachment converted: Macintosh HD:zonnewijzer.jpg (JPEG/JVWR) (0001E644)

"Is this a sundial": not Israel but Boyle Abbey.

[Rudolf Hooijenga]

Hello all on the list,

In my "Is this a sundial?" posting, I said it was in Israel. Wrong, wrong! I
was completely mixed up on that.

The stone is in the museum (the former gatehouse) of the Boyle Abbey ruins
in Ireland.
Interestingly, Mario Arnaldi hit the nail on the head; he spotted my mistake
at once (see below).
Many other list members responded as well, which shows once more what a
great bunch of people you are.

I suppose I shall wash my mouth with geography soap, and thereafter study
Mass Dials - I gather the last word on _those_ has not been spoken yet?

My parents are not particularly interested in sundials so did not ask
further.

52° 30' N; 4° 40' E
Rudolf

Dwight Roberts said:
>Looks like a depiction of a Roman Wagon Wheel to me.  Did she say if there
>were similar stones around?  Size?

Tony Moss:
>As the markings appear to run for 360° I doubt if it is a sundial.  If you
were to lay it flat however, then place a spinning pointer with a pivot >in
the central pit, you would have a primitive wheel-of-fortune.

Richard:
>Just a pretty geometric design ?

Ronit Maoz
>Do you know where was this picture taken? Please let me know.

and, of course

Mario Arnaldi said:
>are you sure that is an Israeli sundial?
>I ask you this because the same identical photograph (yours is a better
>one), has been published on the BSS Bulletin 98.3 Oct. 1998, in an article
>by Andrew J. Ogden headed "Mass dials in Ireland". According to the author
>this is a sundial coming from the Cistercensian Boyle Abbey Co. Roscommon,
>Ireland. According to the author the stone was discovered in one of the
>walls of the Abbey, and now preserved in the Gate House visitor's centre.

>Now the question is: who is wrong?

>I'm really interested knowing the true
>Thank you.

Well, I was wrong, I just got the name of the country wrong..

Thank you all for your response!

Re: Chichen Itza echo effect

[Rudolf Hooijenga]

It is rather a late reaction, but I thought you might enjoy the following
observations:

Echoes by stairs
"I would like add to this a rather remarkable observation that I did when I
was at Chantilly de la Cour, by the equestrian statue. A stair of ... steps
descends into the garden, where a fountain continually murmurs.When at the
bottom one places oneself between the stair and the fountain, one hears from
the direction of the stair a resonance that has a certain musical sound to
it, and that continues for as long as the fountain works. Locals did not
know whence this tone came or produced improbable explications for it, so
that I wanted to find a better one. I soon found that the tone was caused by
the reflection of the fountain's murmur by the steps of the stair. For any
sound, or rather any noise, that is repeated with equal, small interstices,
gives a musical tone..."
Christian Huygens (Oeuvres Complètes, 10, 570), 1693.

Whistling echoes
"An observer is unconsciously always hearing the sound of his footsteps,
which is different according to the nature of the road and its surroundings.
Especially at night, when all is quiet, we notice sometimes how that sound
may suddenly become quite peculiar, almost metallic: each step sounds like
"tyiuuu". It always turns out that a fence is beside the road, and on
further investigation this proves to be the cause of the whistling echo. The
fence should be at least four meters, the distance between the rods too
small nor too large. Explanation: the sound of the step in S is reflected in
turn by rods A, B, C, ... , L, M, N, ... (or rather diffracted, Huygen's
principle!). The weak echoes reach our ear not at the same time, but one by
one, because SAS, SBS, ... , SLS, SMS, .. are gradually longer. The
triangles LPM, SAM are similar, so the difference for two rods 2PM = 2LM sin
alpha, and the frequency of the reflected sound is 340 / 2LMsin alpha. At
every step first the closest, then the more remote rods are involved; sin
alpha is first zero, increases and approaches 1. One hears, then, a very
high pitch, that soon becomes lower and approaches a fixed limit. If the
rods are, for example, 17 cm apart, the frequency of this "final pitch" is
1000 Hz, still rather high. This is in fact what one hears, but the rapid
pitch change does not admit of an accurate estimate of pitch... "
Dr. M. Minnaert (of "Light and Colour" fame), 1943.


- Original Message -
From: John Carmichael <[EMAIL PROTECTED]>
To: Roger Bailey <[EMAIL PROTECTED]>
Cc: 
Sent: Tuesday, March 21, 2000 4:03 PM
Subject: Chichen Itza echo effect


> Hi Roger:
>
> I've enjoyed your postings about Chichen Itza as it is my favorite pyramid
> in Mexico.  Here are a couple of unrelated tidbits that I thought might
> interest you.
>
> When I visited the Chichen Itza pyramid years ago, I noticed that that if
I
> stood in front of the "good " side (not the side that is still in ruins)
and
> clapped my hands, the most curious echo I've ever heard resulted that
> sounded like "zing".  Even the guide didn't know about the echo
effect.
> Later in the day of my visit I saw a bunch of tourists clapping their hand
> imitating the guide!
>
> Also, I love building sand castles when at the beach, and the Chichen Itza
> pyramid is one of my favorites things to build as it is fairly easy to do
> and very erosion stable.
>
> Take care, and enjoy your warming temperatures!
>
> John



Attachment converted: Macintosh HD:fluiten.gif (GIFf/JVWR) (0001B69C)

Re: Measurements on the Equinox

[Rudolf Hooijenga]

Yes, yes yes! Laying out lines is really fun and healthy.

To derive the meridian from the east-west line, you don't even have to use a
Pythagorean triangle.
If you peg two points on the E-W line (not too close together) and connect
them with a long rope, you can pull the rope taut first on one side of the
E-W line, then on the other, each time grasping the rope in the same point.
That point can be anywhere on the rope, although not too far from the middle
(of the rope) is best.
If you mark the two places you can reach that way, you have two points of
the meridian.

Have fun!

Rudolf

- Original Message -
From: Wm. S. Maddux <[EMAIL PROTECTED]>
(...)
Although it might seem a bit like watching the grass grow, a dialist
can find peculiar, but real, pleasure while doing this, just to see the
the straight W to E line reveal itself again, as it always has.

Later you can draw the local meridian at a right angle, anywhere
along this established line, which is a most essential thing to know
for any dialing project.  (The good old Pythagorean ratio of 3:4:5
for the sides of a measured right-triangle is a good way to lay off
the right angle.)
(,,,)

Zonnewijzerkring Bulletins Re: Meridian Line Question

[Rudolf Hooijenga]

Fer, congratulations with the Sawyer Dialing Prize !

On the Roman Surveyor's problem, I can add to Fer's article the summary that
I made of it.
I have added the pictures of Fer's article to the summary.

It is on

http://www.rhayward.demon.nl/sundial/sum99-4/sum99-4.htm#Roman

Some days ago, I have also added (much too late, admittedly) summaries of
the Bulletins 00.1 and 00.2
All can be found on

http://www.rhayward.demon.nl/


Rudolf

- Original Message -
From: fer j. de vries <[EMAIL PROTECTED]>
To: Allan Pratt <[EMAIL PROTECTED]>; Sundial Mailing List

Sent: Friday, September 08, 2000 10:39 AM
Subject: Re: Meridian Line Question


Hi Allan,

Yes there is.
The old Roman surveyors used 3 shadowpoints of a vertical (pin) gnomon to
find the east-west line, thus also the nort-south line is known.
It is even possible to construct a sundial on any flat plane with only the
knowledge of these 3 shadowpoints.
It isn't necessay to know the latitude or the orientation of the plane.
I wrote an article (in Dutch ) about this method in the bulletin of De
Zonnewijzerkring, nr. 4, 1999.
This article is based on a publication in French on the Internet by Yvon
Massé.
http://www.union-fin.fr/usr/ymasse
Title: Comment tracer un cadran solaire incliné et declinant a l'aide de
trois observations d'ombres inégales.

Best wishes, Fer.

Re: New California DST

[Rudolf Hooijenga]

Great..!  I suppose it will be implemented as of Sunday next?   ;-)

Rudolf

- Original Message -
From: Ron Anthony <[EMAIL PROTECTED]>
To: 
Sent: Monday, March 26, 2001 8:07 PM
Subject: New California DST


> All,
>
> The other day I heard on the radio that some politcians has proposed a 2
hour Daylight Savings Time offset to save energy.
>
> ++ron
>
>
>

Re: Time Zones

[Rudolf Hooijenga]

Which reminds me of an attractive puzzle I once saw in Wireless World.
Suppose you have a lot of pieces that fit together to form a hollow sphere.
Think for example of the patches that make up a soccer ball, only thicker
perhaps.
Suppose further they are all magnetised (magnetized?) with N on what is
going to be the outside, S on what is going to be the inside.
The fun part is that nothing fundamental is keeping you from adding pieces,
side by side, to make a growing sphere. Of course they will repel each
other, but that's another problem. All the while, you will have magnetic
lines of force from the N on the convex side, through what will eventually
be an ever decreasing hole, to S on the concave side.
The interesting question is: what happens when you plug up the last hole?
And why? What will the force on the last piece be, trying to keep you from
plugging the hole shut; compared with the other pieces; larger or smaller?

Can we affix a magnetic style triangle to it in order to manufacture a
sundial? OK, this one is a bit obvious, but it keeps the message on topic
;-)
Rudolf


- Original Message -
From: Tony Moss <[EMAIL PROTECTED]>
Cc: sundial mailing list 
Sent: Friday, March 30, 2001 9:03 PM
Subject: Re: Time Zones


> Fernando contributed:
>
> > Or else we can make the sphere to be
> >magnetic and attract our feet, magnetic too, with opposed
> >pole ;-)
>
> Now that IS a novel concept: a magnetised sphere with one pole at its
> centre and the other spread all over its surface. A sort of magnetic
> Klein Bottle.  It's an attractive idea.
>
> Ouch!
>
> The dux flensity near the middle would be interesting too.
>
> Tony Moss
>
>

Re: moon shadow

[Rudolf Hooijenga]

Please check out the following site:
http://www.badastronomy.com/bad/tv/foxapollo.html

where the author has taken the time to debunk every single hoax claim. A
good read, even if some of it is obvious to most of us on the list.

Of course a sundial will work. But with no atmosphere, a guy in a white
spacesuit is also a good source of light, to say nothing of the lunar
lander, some rocks, the soil itself..
Oh yes, and the flag. Try unsquashing a piece of cloth from its tiny hold,
and holding it out on a stick, with NO wrinkles showing.  :-)

Have fun!
Rudolf

- Original Message -
From: Frank Evans <[EMAIL PROTECTED]>
To: 
Sent: Thursday, April 12, 2001 5:29 PM
Subject: moon shadow


> Greetings fellow dialists,
> A recent news item suggests that one in five Americans doubt that the
> Apollo 11 moon landing in 1969 took place, that it was in fact a hoax.
(..)

Re: Oughtred

[Rudolf Hooijenga]

As for "Oughtred", I never gave it a thought, always having assumed it was
"Ought" as in "you ought to do this" plus "red" as in the colour.

A famous family of packet drivers for (among others) Ethernet cards comes
from a firm called Crnwyr.

Just to be on the safe side, there was a .wav file on their web page that
pronounced this name for you.

Unfortunately I coul not locate the page just now (www.crnwyr.com pulled a
blank).

Rudolf

Bulletin summaries

[Rudolf Hooijenga]

Hello all,

I have uploaded the summary of Bulletin nr. 76 (2001-2) to my homepage.

To my horror, nr. 75 was not there- I must have completely forgotten to
upload it.
I have uploade that, too (2001-1).

Converting from Word to HTML I received an error message about some language
page or other. Clearing the cache and reading back from the server,
everything looks OK here, but experience tells me that does not say all.
If any characters look funny (accents, Greek) or other ill effects manifest
themselves, please drop me a small note. Same for language use... ;-)

Have a good read,
oh yes and have a look at the analemmatic being constructed in front of my
house. It's on the entry page.

http://www.rhayward.demon.nl

Regards,
Rudolf

Re: Sundial Trick Photography

[Rudolf Hooijenga]

Hello John and indeed all readers of the list,
 
somewhat less important but because I found it nicer to look at,
I "un-distorted" the photograph of my house (the one that is on my 
homepage, see below) this way.
It was taken from a truck for a good overview, but that had made verticals 
go wider as they go up, which looks very strange.
I used the "perspective" distortion to make doorposts, rainpipes etc. run 
almost vertical and parallel in the picture.
 
Happy photographing!
Rudolf
http://www.rhayward.demon.nl
for summaries of the Bulletin of the Dutch Sundial Society
 

  - Original Message - 
  From: 
  John Carmichael 
  To: sundial@rrz.uni-koeln.de 
  Sent: Saturday, October 06, 2001 4:31 
  PM
  Subject: Sundial Trick Photography
  
  Hi all,
   
  I'm sure you all have had problems photographing 
  sundial faces because you are not able to get your camara centered 
  directly over the center of the dial face.  This is always a problem in 
  photographing vertical wall dials and horizontal doials that are on a high 
  pedestal. These off-center photo angles distort the look of a sundial and turn 
  square sundials into rectangles and round dials into elipses.
   
  But I discovered that by using digital editing, 
  you can stretch or compress a photo so that it appears that camara 
  was directly over the dial!  I discovered this while using the 
  "perspective" and "distort" features of Adobe Photo Delux.
   
  To see an example of what this technique can do, 
  look at the NASS Registry fotos of the Flandrau Heliochronometer, dial # 
  464, Tucson Arizona. The first foto I took from a ladder. The 2ond foto below 
  it is the exact same foto artificially corrected to compensate for the 
  perspective distortion. The difference is amazing!
   
  I think this is a wonderful tool for those 
  of us who photograph sundials.
   
  John
   
  John L. Carmichael Jr.Sundial 
  Sculptures925 E. Foothills Dr.Tucson Arizona 85718USA
   
  Tel: 520-696-1709Email: [EMAIL PROTECTED]Website: 
  

Bulletin 2001-3 summary

[Rudolf Hooijenga]

Hello all readers,

I have just placed my English-language summary of the 2001-3 Bulletin of the
Zonnewijzerkring (Dutch Sundial Society) on my homepage.
If you like, please visit www.rhayward.demon.nl and follow the link for
Summary 01-3.

There is also a link to the homepage of the Zonnewijzerkring itself.

While it is not in the "history" section of the BSS Sundial Glossary, it may
bear pointing out that we are going to celebrate the Zonnewijzerkring's 25th
anniversary - also the 25th of the Bulletin, but you won't find summaries of
all of them..

Regards, and have a happy New Year;

Rudolf

Web woes

[Rudolf Hooijenga]

Good morning (or to taste/location),
Wanting to check sunrise/set, I cannot seem to get the naval observatory on
http://aa.usno.navy.mil/

in my browser. I thought this was the newest site they were on.
Any ideas?
Best regards,
Rudolf

Re: EXCEL-Sheets

[Rudolf Hooijenga]

John (and possibly others), you could try this trick:

http://world.altavista.com/urltrurl?lp=de_en&url=http%3A%2F%2Fwww.astroexcel
.de%2Findex.htm

It will take you to the Altavista translation site, with the URL and the
languages already filled in. You will get sort of a translation.
You can also click on the links, and they too will get translated.

It amazes me what this translator will do - I use it a lot to surf Japanese
elecronics sites, as well as Russian radio sites...

Rudolf

- Original Message -
From: John Pickard <[EMAIL PROTECTED]>
To: 
Sent: Monday, May 13, 2002 2:39 AM
Subject: Re: EXCEL-Sheets


> Josef,
>
> Yes, a wonderful site judging from the diagrams and tables. Unfortunately,
I
> can't read German. Does anyone know of a similar site in English please?
>
> Cheers, John
>
> [EMAIL PROTECTED]



-

Re: EXCEL-Sheets

[Rudolf Hooijenga]

Sorry, for some reason it will not work like this.
Meanwhile, just go to

http://world.altavista.com

and just fill in (or paste) the url
http://www.astroexcel.de/index.htm
in the spot provided and choose German to English (or something else)
;-)

- Original Message -
From: Rudolf Hooijenga <[EMAIL PROTECTED]>
>
>
http://world.altavista.com/urltrurl?lp=de_en&url=http://www.astroexcel.de/in
dex.htm
>


-

Re: Images

[Rudolf Hooijenga]

Hello Tony,

the pictures sound quite good. Could you possibly squeeze me onto your
mailing list as well?
Thank you very much.

Rudolf

- Original Message -
From: "Tony Moss" <[EMAIL PROTECTED]>
To: "Sundial Mail List" 
Sent: Saturday, June 15, 2002 9:20 AM
Subject: Images


> Fellow Shadow Watchers,
>Judging from the response to my offer of JPEGs etc
> of the 3D model there are several List members who didn't receive the
> original message several weeks ago.  The images will be posted late on
> Monday to allow for late arrivals.
>


-

Re: Analemmatic EQT Correction

[Rudolf Hooijenga]

Hi all,

I didn't receive the pdf, but apparently some others - not all - did. Any
thoughts?

Willy Leenders wrote:-
 >Hi Roger,
 >Thank you for sending the sketch "DST Epicycle.pdf".

Willy, would you send me a copy of the pdf? Dank je wel!

Rudolf
52-30N 4-40E


- Original Message -
From: "Roger Bailey" <[EMAIL PROTECTED]>

Have a look at the sketch
"DST Epicycle.pdf" attached to the accompanying email to see the basis for
this idea. The sketch is rough and attached to the other email to get it
past the size filter. The attachment is under 20 kb so I hope it works.



-

Summaries of the Dutch Sundial Society Bulletins

[Rudolf Hooijenga]

Hello fellow sunggazers,

I am happy to announce that, after a silly incident in which I broke an
ankle and disfigured my poor nose, everything is almost back to normal.

This weekend the new Bulletin (2002-3) was sent to our members. At the same
time, the English(-like) summaries of both the 2002-1 and 2002-2 Bulletins
were finished. You can find them on my website at
www.rhayward.demon.nl

The idea is that summaries are used by non-Dutch speakers who receive the
paper Bulletin. Anyone else might miss the drawings, but who knows, some may
be added later. Check often- every half year or so..  ;-)

It is still one of my wishes to make this a better-looking webpage, but
meanwhile, the texts are there..
Have fun!

Rudolf




-

Re: How do we call the equinoxes?

[Rudolf Hooijenga]

Hello Anselmo and all readers,

> Don't you think it'd be better to call the equinoxes 'ascending
> equinoxe' and 'descending equinoxe' instead of 'vernal equinox'
> and 'autumn equinox'? Do you know if the International Astronomy Union
> said something about this?

All I can find in a quick search on the internet is a lot of definitions
using the J2000 equinox, and the "vernal equinox", even in places describing
an "ascending node" of some body.
So, "ascending equinox" seems not be used so often just yet.
Personally, I like "vernal", even if your suggestion does make sense.

> PS: By the way, I am under a persistent 6-week cloudy sky which covers
> the Sun all day... please confirm that the Sun is still there :-D

Today, I noted a bright luminous phenomenon in the sky, somewhere behind the
haze, in - as far as I could make out so quickly - the approximate position
the sun would normally have occupied. I therefore believe it possible that
the sun still exists.

Rudolf
52-30N 4-40E



-

Re: Cardinal Direction Software

[Rudolf Hooijenga]

Hello,

I tried the Cardinal Direction program and it is really quite handy.
I mean, it's one thing to know how to calculate it, but quite another to
have an application that will do this for you at the mere press of a key.
Thank you!

One thing that would be nice (I know, everybody is asking things of you..)
is some feedback on the date input.
(So that, when I input "08/03/2003", somewhere in the output it will say "
August 3, 2003")

The reason is, that when I try it today, using 08/30/2003, the program will
work correctly for today - of course! -, but when I accidentally use
30/08/2003, it will _also_ work correctly for today.

This sometimes mixes me up, especially when the day number is below 13, and
I never know if the program turned the day and month around this time, or
not. Having the input date in the output would confirm the entry.

The same goes for your other execellent tool, the sundial align program.


>   Using the vertical string method, an east
> west line is much easier to mark than a north south one, because the sun
is
> lower and so the shadow stays sharp over a longer length.

In these parts, the sun does not go very high at noon, less than 40 degrees
now (only 14 in winter, poor us). The distance between the top of the string
and its shadow is then not very much longer than in the evening (or morning)
for the same shadow length.
But of course, with higher noon sun, you are no doubt correct.

Regards
Rudolf Hooijenga
52°30'N ; 4°40'E

- Original Message - 
From: <[EMAIL PROTECTED]>
> I just finished writing a tidy little program...


-

Re: Cardinal Direction Software

[Rudolf Hooijenga]

Bill,
Thank you! What rapid service!
I can now easily see if I have input the date correctly. I had a hunch that
my Windows country settings were turning date and month around, and this is
indeed what happens. Now, it's no problem anymore because I can check.
Great!
Rudolf

- Original Message - 
From: <[EMAIL PROTECTED]>

Good idea, thank you.  I have now added this to the display.- Bill

> One thing that would be nice (I know, everybody is asking things of you..)
>  is some feedback on the date input.


-

Calculations help requested for Malaysian dial

[Rudolf Hooijenga]

Hello all on the List,
I received this email on my private email account and thought I'd forward it
to the list. Perhaps someone might like to have a look into this question.

For all, happy days in whatever suitable way!
Rudolf

--- quote ---

From: N.Ravichandran [mailto:[EMAIL PROTECTED]

Hello,
I am a consultant keen to promote a project in Malaysia a sundial similar to
the one in Invercargil in NZ, for sun shade on specific line on specific
date and looking for an astronomer who can help me to calculate the details
and a designer to work with me on this project.
Pls let me know the contact details of such persons.
Have a nice day
N.Ravichandran

--- unquote ---


-

Summary 80 (02.3) online

[Rudolf Hooijenga]

Greetings, sungazers!

I have placed a summary of the Zonnewijzerkring Bulletin 02.3 on my website.

Late, as always, but still nice to have alongside your paper copy.

The Zonnewijzerkring, or Dutch Sundial Society, was founded in 1978 and so
celebrates its 25th anniversary this year.

Check for news on the website of the Society,
http://www.de-zonnewijzerkring.nl/

Have fun, mind the equinoctium;
Rudolf


-

Re: Summary 80 (02.3) online

[Rudolf Hooijenga]

Hello again,
In my hurry to get it over with as long as I was going to get it over with,
I wholly forgot to tell you where that website _is_.
Luckily Willy Leenders kindly reminded me, or you would have been searching
till Spring (N) / Autumn (S)

It is http://www.rhayward.demon.nl
and then scroll down a bit for further links.

There is also a link on the De Zonnewijzerkring site.
By the way, if any of you native or just-as-good speakers of "The Queen's
Own"  have any tips that may improve the translations of "Article of the
month", "Work by members" or "Sundial of the month" columns, I am always
learning, so.. fire away.

- Original Message -
From: "Rudolf Hooijenga" <[EMAIL PROTECTED]>
> I have placed a summary of the Zonnewijzerkring Bulletin 02.3 on my
website.
>


-

Re: Construction Project

[Rudolf Hooijenga]

Hello Tony and other readers of the list,
either I was not subscribed then, or I skipped it because I was not going to
work on aluminium,
but I would be really interested in a repeat now. Would you please?
Thank you,

Rudolf
52-30N 4-40E

- Original Message - 
From: <[EMAIL PROTECTED]>
(...)
>
> Aluminium doesn't engrave very well so you might consider producing your
> scales etc. by anodising.
(...)
> I published detailed notes on the SML on the practicalities of this
> process some years ago but can repeat on request.


-

Re: Construction Project

[Rudolf Hooijenga]

Tony,

thank you for your prompt reply. I'll have some digesting to do!
There are always scraps of aluminium in the workshop, so I shall "work" on
these first, and see what happens.

Not that it has anything to do with the above, but I was asked to prepare a
10 minute lecture on any subject NOT related to air traffic control, to see
how I would stand up as a lecturer  ;-)
I thought I would just touch on an interesting snippet of transmission line
theory (sounds worse than it is), but two of my collegues specifically
requested the subject of sundials.
The thought had not even crossed my mind yet, but I think I will do it, too.

Regards from a sunny Heemskerk (52-30N 4-40E)
Rudolf


-

Re: On canonical hours

[Rudolf Hooijenga]

Mario,

I don't know about the others, but I would be interested to see your answer
as well.
This is something I know very little about, so your views would be valuable,
perhaps to more people on the list.
My best regards,

Rudolf - 52.30N 4.40E

- Original Message - 
From: "Mario Arnaldi" <[EMAIL PROTECTED]>

> However, I'd be very interested in your distribution of canonical hours.
-

I'll do in private to not bore the list
---

Mario Arnaldi


-

Re: norwegian sundials

[Rudolf Hooijenga]

Thank you Fred for this great link.
I found the first two sundials on this page myself when in 
Oslo in 2000.
I did not speak Norwegian then. I do now, and it is great to 
pick up sundial-related expressions this way to add to my 
vocabulary.
Thanks!
Rudolf
52-30N 4-40E
 

  - Original Message - 
  From: 
  Fred Sawyer 

  To: Sundial List 
  Sent: Monday, October 06, 2003 3:26 
  PM
  Subject: norwegian sundials
  
  Some Norwegian sundials:
   
  http://nordnorsk.vitensenter.no/himmel/solursida/norskesolur.htm
   
   

Re: Plekhnatons (slightly off-topic)

[Rudolf Hooijenga]

Peter,

I don't know what one is either, however it occurs to me that Aton, in
ancient Egypt, was the Sun god.
Perhaps the sundial was called "sun-***" where *** is the Plekh part. The
Greeks could have borrowed the word from the Egyptian language.


- Original Message - 
From: "Peter Tandy" <[EMAIL PROTECTED]>
Subject: Plekhnatons (slightly off-topic)


-

Re: Dialist's Companion

[Rudolf Hooijenga]

Thank you for the description, Fred.
However, somehow I felt knew this already, so I must have been 
in the program somewhere.
 
When in the main screen, hit F1;
then, select Dates and Times.
 
Ah! _That's_ where I've got it from.
 
great program, that... thank you Fred, and Bob.
 
Rudolf
 

  - Original Message - 
  From: 
  Fred Sawyer 

  To: Sundial List 
  Sent: Thursday, September 25, 2003 9:11 
  PM
  Subject: Dialist's Companion
  
  In a recent response to John Carmichael, I 
  referred to some capabilities of the Dialist's Companion program.  It 
  seems that a number of people where unaware of these features.  After 
  checking the Help page, I discovered that we evidently did not document them - 
  so no wonder that they are still a bit mysterious.  This will give a 
  little more detail:
   
(...)

Re: Oblate Spheroid correction for computing distances?

[Rudolf Hooijenga]

Hello toves,
 
quote from text below..
"At this level of accuracy, what is meant by the "position" of 
a station starts to get lost in the noise of the planet's shape."
 
There are (of course) programs that will try to tell you to the nearest 
inch what the distance is between any two points on the globe, and throw in the 
azimuth for good measure.
 
The following text, admittedly a bit longish, I copied from an 
amateur radio book. It is about programs giving "distance and bearing" between 
two points. Just replace "station" by "location" and you're allright.
 
I did not include the actual (Basic) programs. If anyone wants them, let me 
know. They are from 1985. But it is really the reasoning I thought was 
interesting.The text is by John Morris, GM4ANB for illuminati. We meet him just 
after he has explained a basic, sphere-based program.
 
-- snip --

Latitude correction
So far it has been assumed that the Earth is a perfect sphere. Of course it 
is not, being somewhat flattened at the poles and bulging at the equator. It is 
convenient to assume that the Earth is ellipsoidal; that is a cross section 
through the equator is circular, but a cross section through a line of longitude 
is elliptical.
This assumption introduces two corrections. The most obvious one is that the 
distances must now be measured along the boundary of a more or less eccentric 
ellipse. Surprisingly, this is a relatively small correction.
A rather larger error arises because latitude is not quite what most people 
think it is. Fig 5.2 shows a cross section of the Earth through a line of 
longitude. The eccentricity is much exaggerated. For a given point P, on the 
surface of the Earth, the angle ECP is called the central angle. It is this 
angle which all of the
preceding distance and bearing formulae assume is the latitude. In fact the 
latitude is calculated from the normal to the surface of the Earth at P, giving 
angle ETP. This arises from the way latitude was historically measured; by the 
positions of the stars relative to the horizon.
The distance a is called the semi-major axis of the ellipse, and b is the 
semi-minor axis. For a given latitude the central angle can be calculated as 
follows:
Tan(central angle) = (b/a).(b/a).tan(latitude)
For the Earth the value of a is about 6378km, and b is about 6356km. The 
average of these, 6367km, can be used as an average Earth radius, as was done in 
Programs 5.1 and 5.2.
Program 5.3 shows the lines which should be changed or added in Program 5.2 
so that central angles are used instead of latitudes. Line 30 sets up a few 
constants giving the size and shape of the Earth. The new subroutine, in lines 
2000-2100, is very similar to the original in Program 5.2, but instead of the 
latitudes uses the central angles, Nl and N2, in the formulae. The latter are 
calculated in line 2000 using the above formula and the assumed shape of the 
Earth.
A typical run after the lines of Program 5.3 has been included is shown in 
Fig 5.3. The results are similar to those from Program 5.2, but not 
identical.
In this version of the subroutine the maximum distance error is reduced from 
0.5% to about 0.2%. The residual error arises because the distance calculation 
itself still assumes a spherical Earth, even though the correct central angles 
have been used.
The azimuth error is extremely small. The bearing from one point to another 
does not depend on the shape of the Earth, only on the central angles. Once 
these are known no further correction for the shape of the Earth is needed.
Ellipticity correction
Program 5.4 shows a replacement subroutine for those in Programs 5.2 and 5.3 
which takes account of the ellipticity of the Earth when calculating distance. 
As may be seen, getting the last few tenths of a percent of accuracy is a messy 
business.
The mathematics behind this routine are rather long, but the steps involved 
can be summarised as follows:
Lines 2000 to 2070 find the central angle and azimuth, as previously. The 
rest of the routine finds the distance.
Lines 2080 to 2170 find the great circle on which the two stations lie. This 
great circle is in fact an ellipse, its ellipticity depending on its inclination 
to the equator. If the great circle intersects the equator at a large angle 
(such as a line of longitude) the ellipticity will be the same as that of the 
Earth. If the angle is small the ellipticity will be small; in the case of the 
equator itself it is zero. AL is this angle of intersection. XI and (XI+CA) are 
the angular distances round the great circle from the equator of the two 
stations. EP is the square of the eccentricity of the ellipse on which both 
stations lie.

Once the ellipse of interest and the positions of the two 
stations on it have been identified lines 2180 to 2200 perform the actual 
distance calculation. The formula in line 2200 is an approximation to an 
infinite series in EP. As EP will, for the Earth, always be small (its maximum 
is about 0.00

RE: No decision on future of leap seconds

[Rudolf Hooijenga]

You need, on average, to add more leap seconds than subtract because the earth 
is on average a little slower than the atomic reference. But that in itself 
does not mean Earth is slowing down.

 

Suppose that the Earth kept absolutely constant speed, without slowing down at 
all, then there would be a fixed speed difference with a corresponding number 
of leap seconds each year to be added or subtracted – just as when,  when a 
clock needs to be adjusted by a minute each and every month, it means that its 
speed is constant – although slow (or fast).

 

In fact, the Earth does slow down – and not just lately –, but this effect 
amounts to about 17 microseconds each year on average, and would only 
necessitate an extra leap second every sixty thousand years or so. The 
day-to-day fluctuations are much larger than this.

 

All the best,

Rudolf Hooijenga 52.5N 4.7E

 

 

Brooke Clarke wrote: 

[…] In order to keep the UTC1 correction below a second leap seconds can be 
added or subtracted as needed, but since the Earth is slowing down lately they 
seem to all be adding a second. […]

 

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RE: Diamond Fuji

[Rudolf Hooijenga]

Thank you, Frank and also Roger; that sounds quite plausible.
Really, the eye plays the same trick sometimes. At night, a street lantern
will often appear to eat up the top half meter of its supporting pole. :)

Rudolf
52.5N 4.7E

-Oorspronkelijk bericht-
Van: Frank King [mailto:f...@cl.cam.ac.uk] 
Verzonden: donderdag 7 januari 2016 16:44
Onderwerp: Re: Diamond Fuji

[...] This is a big challenge for a camera and what we are seeing is local
over-exposure.
On the image sensor at the back of the camera, there is spill-over of light
onto neighbouring pixels.
[...]


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Happy PI Day!

[Rudolf Hooijenga]

Hi everyone,

Although getting on for time here in Europe, I suppose it is never really
too late to wish everyone a Happy Pi Day!
http://en.wikipedia.org/wiki/Pi_Day

Rudolf

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RE: Build your own Cut Out Paper Vertical Sundial with google

[Rudolf Hooijenga]

Thank you Damia,

What a fun thing to do. I am glad the declination bug was sorted out.

I am now looking at four different sundials and they all seem to work as
accurately as I could fold and glue them. Next, I will try a window sundial.

Now to find a way to keep the style triangle square to the dial face (I
mean, even when it is dry weather).

Rudolf, 52 30 N 4 40 E

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