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The third set of magnetic observing procedures was related to observations made on overland sledge journeys. The data from field observations during such journeys was less reliable than data from the fixed observing stations. The vagaries of accurate position fixing was a factor. Most position finding was estimated using dead reckoning: a combination of distance determined using a sledge meter (something like a cycle wheel at the stern of a sledge with a counter attached) so that distance travelled could be determined, and bearing, generally determined using a hand-held compass. In the Ross Sea region the compass was of little practical use in navigation due to the proximity of the magnetic pole where the weak horizontal force meant that the needle was sluggish and the declination was great. 
Bernacchi’s prismatic sledging compass on display in the Canterbury, Museum, Christchurch. More accurate position finding was performed using theodolites or sextants and sun sights, as planets and stars are mostly invisible during the perpetual sunshine of the Austral summer in Antarctica. Celestial navigation, whether on the ocean or on a featureless icy plateau, relied on accurate timekeeping. Delicate precision timepieces do not react well to low temperatures or constant jarring amongst the luggage on a moving sled. Even when the location of a set of observations was accurately determined, the magnetic instruments used on the trail were difficult to manipulate in freezing, exposed conditions and, like timepieces, would have been affected by the rough journey. Directory: Upload Upload -> 587 Return function, r i(X) r i(0) r i(1) r i(2) r i(3) 1 0 2 4 6 Thermal Station, I 2 0 1 5 6 3 0 3 5 6 10 Upload -> Department of science and humanities department of mathematics part-a questions and answers Upload -> The Case Against the nypd’s Quota-Driven ‘Broken Windows’ Policing What Is It? Upload -> For want of a nail Upload -> Traditional British values Upload -> Tv shows, Made for tv movies, Mini Series & Internet Programs Shot at Paramount Ranch Upload -> Ownership Models There are two different types of ownership models Upload -> Police Militarization Upload -> City of rising star regular meting thursday, july 14, 2016 Upload -> Township of winfield Download 4.64 Mb. Share with your friends:
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