Sundials

Joseph Moxon "Mechanick Execises",London England 1703

Now let me try to say that! If the sun can cast a shadow from a point onto a surface then you can make a SUNDIAL. The shadow's position on the surface, which is a function of the sun's angle from straight UP, can be calculated. Also since the sun's position is a function of time, the shadow position can be marked as an hour instead of an angle.

The references provide both arithmetic and graphical procedures for the simplest of sundials. However I was looking for the arithmetical solutions for abnormal planes (like the roof on a shed) and couldn't find any. I took the graphical procedures of Moxen and derived the appropriate formulas. These I incorporated into a computer program for my PC (using visual basic) to calculate the hour lines on any surface orientation for a given latitude and longitude.
I have designed and made sundials that go on fences and shed roofs. I have also made shepard's dials, polar dials, armillary dials and anammelatic dials. The computer program is set up to handle all of these dial types.

	This is an armillary dial and was made from iron tires off an Amish buggy. This dial can be set for Standard Time or Daylight Saving Time just by rotating it 15 degrees about its axis.It is currently set for Daylight Saving Time. It shows the current time at Radnor Forge as 11:30 DST. Our dog (in the background) doesn't really care.

	The most comon kind of Sundial is a horizontal plate with the hour lines inscribed upon it. The hardest part is to actually manufacture it. Wood, a material easily worked, has to be continuously treated to withstand the elements. I make my horizontal dials, some of which are shown to the left, by casting them from aluminum.

Molds with patterns removed.	Molds ready to be poured.

Molds poured.	Dial "shaken out".

Cut off the gates and sprues and epoxy the gnomen to the plate.