Hi Bill:
Of course you are right that optical resolution is'nt that important when
looking at the shadow's edge cast by a traditional solid gnomon. However, I
think it is important for string, cable, rod or spherical gnomons. It is
also important when designing the width and size of numerals,
Hi Dave and others:
Let me see if I understand your calculations.
First, knowing that 1 arcminute is the limit of visibility, you calculated
that 1 arcminute of width (of a line or point) is equal to a width of .0035
inches at one foot. or .35 inches at 10 ft. and so on.
The table which you so
When I first started using cables for my styles I thought a lot about what
would be the correct diameter cable. On one hand, I wanted the cable to be
as thin as possible, because a thin shadow gives a more precise time reading
than a thick one. On the other hand, if the shadow is too thin,
- Original Message -
From: John Carmichael [EMAIL PROTECTED]
I think it would be more useful for a sundial designer to have the table in
a
more useable form that lists the maximum distance of visibily for
different
widths. (I picked 1/16 inch increments because these are the sizes of
What's all this inches nonsense.
Tsk, Tsk. How could you? !
Patrick
Frank Evans contributed:
What's all this inches nonsense. Anyone would think we were back
landing on the moon or something. Napoleon, thou should'st be living at
this hour.
and we'd tear every bone apart!
Guess who!
Steve Lelievre contributed
snip
- every millimetre of width gives 1 metre of viewing distance
- every 1/16 inch gives 5 feet (actually a little over)
Which is not too far from the '3mm hourline 4 metres up my house wall'
suggested earlier.
Tony Moss.
Hi Frank:
The reason I suggested inches for the optical resolution table was that all
of the metals that we use for gnomons such as rods, spheres, plates, and
cables are sold in inches or fractions thereof, in the US anyway. I agree
that most people who have to do math would prefer to use
Re the comment about Carter and Reagan and metrics. I was a student in
elementary and middle school during both administrations, and I can vouch for
the fact that attempts to teach us metrics were attempted, and it did seem in
vouge for a while at least in the educational system. The problem
