Dear Dialers After my recent post about GPS and sextant I got few replies to me personally. This is really amazing how sextant catches human imagination. No other instrument, whether telescope or theodolite, not to mention GPS, has such fame like sextant.
Note that it is of not much use for sun dialing. It was seldom used for land navigation where you have to emulate the horizon using bowl of water, oil or mercury. On land you have zenith line instead and you may set your instrument using precise bubble levels. This is impossible at sea but there you have the horizon plane and stabilize the instrument using your hand and eye. There was one notable exception in land navigation where sextant was used as the main instrument. It was the heroic era of Arctic and Antarctic exploration, not so long ago. Causes could be few. The first one I think was that most explorers, like Amundsen, Scott, Shackleton and others, were mariners and they felt sextant with their fingertips. Second reason could be that sextant is really handy. It is not very big, nor very heavy and this was of importance when every gram of load mattered. Its set up for work on land is very fast even if not natural. You just put a bowl with mercury (maybe alcohol) on some box or block of ice to have the artificial horizon and that's it. In case of other instruments you would have to assemble tripods, attach the device, level it, orientate and other things. This would add just another activity to your daily duties and some more kilograms to your load. So sextant was certainly more convenient. BTW, when you use artificial horizon like bowl of water for sextant observations you simply measure the angle between the body and its reflection. Sextant is sometimes called "Magic Mirrors" and its influence on people having little to do with navigation certainly justifies the name. As an instrument it is not easy to use for neophites, requires determination and patience during learning period. It always requires devotion and respect from its users, whether experienced or not. GPS is a marvel of modern technology and its use is very easy. No devotion is necessary, just press the button. Because of its price it is available for everyone. Of course it wil dominate. So we are watching the beginning of an end of the glorious sextant era. Slawek Slawek Grzechnik 32 57.4'N 117 08.8'W http://home.san.rr.com/slawek
