NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Nautical Mile, was: Why is a sextant like it is?
From: Trevor Kenchington
Date: 2004 Nov 18, 19:30 -0400
From: Trevor Kenchington
Date: 2004 Nov 18, 19:30 -0400
Alex wrote: > I am sorry, but is seems that "the mile is a minute" > is the DEFINITION of the (n)mile, which was made > just because people wanted to preserve this super-ancient > system of degrees and minutes. The nautical mile was introduced.... > I don't know exactly when, but centuries if not millenia > after this Babylonian hexadecimal system. > (Let Herbert Prinz correct me here. I really don't know much > about history). The nautical mile is quite a recent unit, which seems to have arisen because the length on the ocean surface subtended by one minute of latitude proved to be conveniently close to one Roman mile -- itself the distance covered by 1,000 paces by a Roman soldier (the Romans counting a "pace" from one foot lifting off to its touching down again, in contrast to the modern English notion of a "pace"). The whole topic is apt to get confused because the length of a degree of latitude, the length of a foot, the numbers of feet per mile, miles per league and leagues per degree were all fluid. The earliest close approach (at least in English) to the modern version seems to have come with Norwood's "The Seaman's Practice" of 1637. At least, that is the best answer I can dig out of Waters' "The Art of Navigation" -- a comprehensive but sometimes confusing source. At the opposite end, the origins of the 360-degree circle and 60-minute degree may belong to Babylon but, along with much else of Mesopotamian culture, could be far, far older. Seafaring was at least 50,000 years old and perhaps 500,000 by the time that the Sumerian kings recorded the story of their progenitor escaping a catastrophic flood in his reed ship (complete with breeding pairs of his domesticated animals). Somewhere in that huge span of time, men capable of building seagoing vessels and crossing open water may have felt the need to divide the circle into convenient units, using as system that we know has survived about five millennia and could well have survived ten times longer. Trevor Kenchington -- Trevor J. Kenchington PhD Gadus@iStar.ca Gadus Associates, Office(902) 889-9250 R.R.#1, Musquodoboit Harbour, Fax (902) 889-9251 Nova Scotia B0J 2L0, CANADA Home (902) 889-3555 Science Serving the Fisheries http://home.istar.ca/~gadus