NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Theodilite Shots by Day
From: Peter Fogg
Date: 2002 Feb 4, 12:41 +1100
From: Peter Fogg
Date: 2002 Feb 4, 12:41 +1100
Explorers of the Antarctic, such as Douglas Mawson in the early years of the last century, used a theodolite (or something similar) as their principal method for fixing their position using sun sights and for aligning their compass (which was close to useless so near to the South Magnetic Pole). In summer, weather permitting (his book was called 'The Home of the Blizzard') the sun was just above the horizon and circled it in endless day. When its azimuth was at 90� or 270� the resulting line of position would give them a longitude and at 360� or 180� they could obtain a latitude. In practice, like the rest of us, they took sights when weather permitted, and used ded. reckoning to fill in the gaps. It must have worked, navigating their way back to base camp seems to have been the least of their problems, and they produced accurate maps. By way of contrast, various intrepid souls insisted on crossing from British India into Tibet, particularly during the latter half of the 19th century, as if its blank expanses (on their maps) were an affront. The Tibetans wished to be left in peace and would expel them when they were found so they went disguised, often as Hindu pilgrims. An intrument on a tripod was a teeny bit suspicious so their main tool was the prayer wheel, still widely used in Tibet. Its a bit like a child's rattle, held in one hand, a weight on a string spins a cylinder which is inscribed with a prayer and thus mechanically propelled, hopefully earning much merit. The pundit's version was calibrated to assist them to record the distances covered at a set pace with paper, pencil, and notes kept inside. A sextant was useful in secluded places, not just for fixing a position but also for calculating heights and distances - its mostly up and down country.