Dear John, Here is another, easier Emergency Sundial. Hope this satisfies as well as the last one.
Our research has finally paid off. As you may recall our last quick fix sundial required shoestrings and writing empliments. This newly developed method can now supply an emergency sundial with only a properly facing surface, a few rocks or other lumps and proper use of your body. No longer must you suffer countless hours without a sundial! Find a surface that is parallel to the equator, tilt a table, find a leaning rock, pile up some sand, whatever. For many people, including myself, the angle subtended by a tight fist, looking from the elbow toward it, is very close to 15 degrees. So, stick the elbow down where the gnomon will be and mark off 15 degree marks with rocks, using your fist as a guide, rotating your arm about the spot your elbow is on. ( The back of the fist down is the classical method ). These mark the hour lines. Pop your arm up vertical to the surface and there you are, an equatorial sundial. With this basic dial you can tell pretty close how long it has been since you built it, but still have a large error in where 12 o'clock might be. This error will be composed of meridianal error ( wrong guess where north is ), Longitudinal error ( not right on prime meridian) and the equation of time. Using some other time instrument you can calibrate out this main error by discovering, for existence that 12 on your sundial is really 5:15 PM or some such. A large rock or twig might be used in place of your arm sticking up if you have other things to do than just watch the sundial all the time. You can also make a shadow plane dial instead, using a similar approach, but starting with your elbow away from the sun and telling time by the shadow of the rock that hits your elbow. If further research improves on these latest findings we will happily report them. :-) <g> Edley McKnight [43.126N 123.357W]
