To Rolf Menzl I have caught up on the mail regarding how to measure declination after spending the week-end camping with the Boy Scouts. For several years I have been using sundials to teach the boys some details about orienteering. I have found that when I explain to them how a horizontal dial and an analemmatic dial used together can be used to tell both time and direction, they have a much better grasp of time, maps, stars and other necessities. In order to do this, I have developed a spreadsheet that generates instructions for autocad, which in turn is used to produce a double dial for any location I need.
For measuring the declination of your wall, it would be a simple matter to laminate a printout of a dial like this to a board and make a double dial of your own. I have done this often to demonstrate magnetic declination of a compass, as the dial is accurate enough to check the declination shown on a topographic map of the areas we are working in. The spreadsheet in its current form is not generic enough to send along, as it is written to communicate with autocad through an intermediate program, and none of what I have done is documented. I have attached an hp plot file to this message that can be read by any good graphics program and printed out on a printer. The attached dial is calculated for 38.55 degrees North, 77.25 degrees West (Fairfax County, Virginia). In the event you are able to read and print this file, I would be happy to generate one for your specific latitude and longitude if you like. Steve Harrington
DIAL.PLT
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