NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Reaching the pole. (was Nautical Almanac)
From: Robert Eno
Date: 2002 Jul 4, 21:08 -0400
From: Robert Eno
Date: 2002 Jul 4, 21:08 -0400
George Huxtable wrote: ------clipped--------- > I have yesterday discovered a remarkable book by Peter Ifland (occasional > contributor to this list) entitled "Taking the Stars", about the > instruments used in navigation. Superbly illustrated and very > knowledgeable, it has the best information I have found anywhere about > artificial horizons. Now I must search for my own copy. > > ========================= Eno responds: I was given a copy of that book for Christmas a few years ago. It the sextantophile's (is that a word??) bible. George Huxtable wrote: > My guess is that the vibration of Fuchs' tractors upset the operation of > the compasses when the horizontal magnetic force was low, even if they were > well compensated for deviation (which I doubt). I have come across a > compass installation on a boat in which, even in UK waters, the compass > card would rotate anticlockwise, slowly and continually, whenever the > engine was running. Eno responds It appears that we have similar tastes in reading material. I have a copy of Fuchs' book: "The Crossing of Antarctica" which I have not read for fifteen years. I have also read Hillary's account, the name of which, unfortunately, escapes me at the moment. Both Fuchs and Hillary used a sun or astro compass on their respective journeys. Fuchs refers to a "sun compass" and I seem to remember seeing a photo in Hillary's book, of an astro-compass mounted on one of the converted farm tractors, which he used on his end. Interestingly enough, at least from the material that I have read, there was a bit of friction between Hillary and Fuchs. There's the old strong-willed polar explorer characteristic again! It always puzzled me how they were able to make use of the sun or astro-compass to maintain a heading. I've never used a device called a "sun compass", however, I am intimately familiar with the astro-compass, which has to be levelled with two built-in spirit levels, in order to obtain an accurate heading. Perhaps they stopped every once in a while, levelled their astro-compasses and took a heading off of a distant object. George Huxtable wrote: It's a pity that Amundsen doesn't supply any details about > these aspects of the navigation. An important reason for precise navigation > was the need to locate depots of food and equipment where these had been > left beforehand, and marked by snow-cairns and flags. Eno responds: Yes, it is a great pity. Amundsen supplied so many minute details about the planning, preparation and execution of his expedition but is laconic where navigation is concerned. Perhaps he felt that this was too obtuse a topic to relate in a book intended for the general public. Amundsen's method of finding his cairns was not just a matter of hitting the depot dead on. He took the time and trouble to mark the depots by placing colour coded flags, mounted on bamboo poles, a considerable distance east and west of each depot. In this way, he did not have to find the needle in the haystack, he only had to locate one of the colour-coded flags which would lead him right to the depot. In otherwords he created a target about two miles wide (can't remember the exact distance that he spread out his flags) which is far easier to find than a single snow cairn. Yet another example of Amundsen's brilliant planning and forethought. The guy was truly a professional. Admittedly, I am very biased. Amundsen is one of my heroes. Robert