Hi Walter,
I too thought some small pictures were nice, but, as I have a few
websites I can post items to, I'll do that in the future, so that
those that want to see the pics can, those that don't, wont. I'm
hoping the adobe Acrobat pdf format I've chosen will work for
everyone, since readers are free for most platforms.
On the accuracy thing I have a few comments. For me, time as
characterized by the orbiting and rotating of the earth as
complicated by height, refraction, elliptical orbits, perturbations
and lovely earthly wobbles is the real time. I mean, we live with it
every day and the sun being up makes it day. Again, this beloved
time is actually a set of observations of a number of interacting
processes which are not forever repetitive to the finest structure.
Anyhow, at an observatory I once visited they commonly reflected and
enlarged the image of the sun to about 6 feet (2 meters) in diameter
on a large, long blank white wall with a fine grid and took timed
photos of it as it as it moved rapidly across the wall. They said
they could resolve time to hundredths of seconds with this method.
Using a sextant and accurate tables, fixing on just an upper or lower
limb of the sun, accuracies of better than a second in time are often
made if the position in space is very accurately known. The key to
accuracy appears to be in enlarging the image and using either a
predetermined elliptical shape to measure it's position, or some
fixed point on the edge of the image, or a grid and photos.
An idea to make smaller time intervals more meaningful is to know
that light travels about a foot (11.8 inches) in a nanosecond. So
the difference in time between the path of light at dawn and noon,
being different by about 4 thousand miles is about 0.02 seconds.
I like the spirit and message of your comments!
Edley McKnight
[43.126N 123.327W]
> Hello again, thank you for all for the reactions, but what is wrong with
> my feeling about a second, when I say you can feel it , I mean of course
> you can count in seconds & not in milli- or nano- seconds. I had thought
> about the sharpness of the shadow, but forgotten to mention it.
> Considering the center of a shadow of a thick gnomon I do not like, it is
> to subjective - your eyesight & angle of view may be different as to
> another person. But what about the reverse, instead of a shadow use the
> light. This was used by clockmakers of the past for adjustment of their
> watches. They used a horizontal dial & the gnomon was a small disc with a
> pierced small hole & positioned according the local latitude & looked only
> at noon to the spot thrown on the dial. (as you maybe discovered my
> interest in sundials is in relation with mechanical clocks or watches).
> So, why not with the aid of modern optics, obtain this needelpoint of
> light, the sun is needed in either case, shadow or light;Again, very
> interested in your comments. ( and also, as said, a university for this
> study would be nice, no?) Now on attachments, I am a bit surprised by the
> comments I read, what is prohibitive about pictures ? If it is the price
> of the connection-time, my opinion is, forget your PC & use the
> conventional method offered by the postal services, you will spend money
> in either case & as you know, the speed is uncompatible between the two. I
> started with a 56K modem, after that idsn, & now I have ADSL, fast &
> indifferent to your connection time which may be 24/on 24, the price
> remains the same, & in my country all providers are constantly lowering
> their prices. As to the danger of a virus enclosed in an attachment, you
> have to live with it & trust the anti-virus programs, which you have to
> update often. I personally like pictures in a mail as insertions, & use
> the insertion facility often for drawings taken by my digital camera. So
> long, Walter 50.42.1 north4.33.46 east
>
