Dear Friends,
The NASS Website has added a new feature. We have removed the SunClock
image which took so long to load from the home page.
There is now a Current Data page which can be accessed by clicking
Current Data in the left frame.
The page displays a new java applet written especially for
And you are quite right, Gordon! I jumped to minutes, from seconds...
Something like that usually happens when I nitpick at someone else's typo!
How about 5 and 24 uRad for limiting sizes?
Dave
On Tue, 15 Feb 2000, Gordon Uber wrote:
> Dave,
>
> You are quite correct: 17.45 mrad = 1 deg, no
You are quite correct: 17.45 mrad = 1 deg, not 1 arc minute.
However 4.848 microrad = 1 arc second, or approximately 5 microrad.
You may be thinking of 1 arc mjnute = 0.2909 mrad
Gordon
At 02:13 PM 2/15/00 -0800, Dave Bell wrote:
Whups! You meant a *degree* is ~17 mRadian, didn't you? An
On Tue, 15 Feb 2000, Steve Lelievre wrote:
> From: "John Carmichael" <[EMAIL PROTECTED]>
>
> >...
> >Apparently, ring order and number of
> > rings are not important. Am I correct?
>
> You build your dial with an azimuth scale forming a circular
> arc, like a giant protractor. Since the length
On Tue, 15 Feb 2000, Gordon Uber wrote:
> Third minutes (sixtieths of second minutes) are not in common
> use, although I would note that the third minute of an hour is the period
> of U.S. power main standard 60 Hz alternating current. Coincidence?
Hmm... Surprised I never noticed that! Perh
Andrew James cxontributed:
>My idea is this: is it possible to combine the two points made? Arrange,
>say, two sets each of four posts with three 0.4 mm gaps between, one set
>having slightly wider posts but with the same gap, so as to make three light
>rays the outer two of which diverge by the
Fellow Shadow Watchers,
Casting from wooden patterns is something not touched on
so far as I rarely use castings. For quite a while now I've been making the
patterns for a Mariners' Astrolabe in odd minutes between other jobs. They are
now finished and go to the foundr
Just curious - what use does a company have for so many of these.
The "astro compass" I am familiar with is the military version used in
aircraft for finding true north. It is essentially a heliochronometer on
which one can set latitude, declination and hour angle of the sun. Then the
device is
Let's face it: The Babylonians got it right when they developed the base-60
system. It was applied to the sixth of a circle (one sixtieth of this
being a degree) and the hour, of which we still use the first and second
minutes. Third minutes (sixtieths of second minutes) are not in common
- Original Message -
From: "John Carmichael" <[EMAIL PROTECTED]>
To:
Sent: Tuesday, February 15, 2000 12:27 PM
Subject: Dali dial rings & gnomons
> HI all:
>...
>Apparently, ring order and number of
> rings are not important. Am I correct?
>...
> I know we discussed the Dali azmuthal d
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
HI all:
In the new edition of the BSS Bulletin (vol. 12, Feb. 2000) on page 51,
there is a sketch of an azmuthal (Dali) sundial by John Singleton titled: "A
Horizontal Dial with Equation of Time Built in".
I see a couple of differences in this drawing and similar dials previously
described by Ar
Hi All,
It was my understanding that the analemma against the blue sky was the
original image, then the foreground was pasted in from some completely
different sources.
Mr. de Cicco pointed out that - as Ron mentioned - the shadow of the
chimney is going the wrong way. Once the shadow is wrong,
I reckon the state of the tree is a clue too. It looks deciduous to me, so
we ought to see exaggerated dark veins due to bare branches from the winter
part of the image. The branches will be displaced by winds, so the tree
ought to look blurred. The dark blue sky and dark shades of green in the
tr
As a Physicist who grew up in England I learnt both systems. When I came to
the USA with its decimal monetary system (England was still on the old 240
pennies to the Pound) I learnt an often un appreciated virtue of the
British System. The first time I went to tutor an inner city kid he asked
me t
The normal procedure when photographing the sun is to use
a neutral density filter of density 5.0, which reduces the
light by a factor of 100,000. So even of you took a picture
a week through this filter, it's nowhere near the exposure
needed to register the foreground image.
Andrew James <[EMAIL PROTECTED]> writes:
> My idea is this: is it possible to combine the two points made? Arrange,
> say, two sets each of four posts with three 0.4 mm gaps between, one set
> having slightly wider posts but with the same gap, so as to make three light
> rays the outer two of wh
Tony Moss suggested using a non-diverging sunray after passing between pairs
of posts 0.4mm apart for a heliochronometer.
Art Carlson wrote: But this line is not unique. You will get such
a line if the instrument is aligned toward any part of the sun's disk.
My idea is this: is it possible
Re: my email on a non-diverging sunray after passing between pairs of
posts 0.4mm apart.
Art Carlson wrote:
>
>Careful! It is true that you can produce an (almost) non-diverging
>line of light this way. (By the time the beam has traveled ten times
>the separation between the post pairs, it wil
Message text written by John Carmichael
>I even have a ruler and lined velum drafting paper both graduated in
decimal inches! <
In the UK many (if not most) Imperial measure rulers are graduated
somewhere in decimal inches as well as in eighths and sixteenths and they
have been ever since I was
Fellow Shadow Watchers,
As a teacher within the UK educational system I
went entirely metric from the late 60's. If school examinations were to
be exclusively metric there was no choice. Everything in Imperial
Measure was ruthlessly discarded; not a rod, pole, perch, pec
Peter Tandy <[EMAIL PROTECTED]> writes:
> ... Of course, for some specialised work,
> metric measurements are no better and no worse; atronomers for instance do
> better with the numbers they need to measure huge distances, when in a
> metric form, and physicists with the numbers they need to mea
As a teacher of some fairly typical American (U.S.) 14 - 15 year olds, I
can state without exception that the students do not prefer British
units over metric units, because they don't know either system. My
attitude is, since they don't know either system, I teach them metrics.
Things I have be
Heh heh! I measure in micro, pico, and nano-lightyears...
-Original Message-
From: Tom McHugh <[EMAIL PROTECTED]>
To: Tony Moss <[EMAIL PROTECTED]>; Frank Evans
<[EMAIL PROTECTED]>; Sundial Mail List
Date: Saturday, February 12, 2000 7:24 PM
Subject: Re: metric
>Anyone for cubits? O
Wow, quite a story! I think it's interesting, how much measurements have
been based so much on things within farming, or what people use most.
In high school chemistry I always liked centimeters. They were great! Just
the size of a pinky-nail...Unless I'm getting everything mixed up (it's been
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