NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Comments on the units
From: Alexandre Eremenko
Date: 2006 Apr 7, 14:07 -0400
From: Alexandre Eremenko
Date: 2006 Apr 7, 14:07 -0400
Perhaps this does not fit exactly in the list scope but I will comment a bit about this funny subject of the units. On Fri, 7 Apr 2006, George Huxtable wrote: > | We think of the metric system being firmly established in the world, but > | only a part of it -- measurement of distance and temperature -- is > | universal. I am surprised with this statement. If you subtract the US, from the rest of the world, the metric system if firmly established in EVERYTHING except time/angular measures. Of course there is nothing good or natural about base 10 at all. Bases 8 and 12 are much more convenient for many purposes. I know of one attempt of transfer to base 8 (Charles XII of Sweden tried to introduce it as a general standard. But he died young (and defeated)). > Grads (100, not 90, to the right-angle) still appear on some French maps. In Soviet artillery, at least when I served for a brief period in 1975, the angle measurement unit was called simply "one division". There were 6000 divisions in the full circle. The reason for this was that 6 is a reasonable approximation to 2pi. Thus an object of size 1 meter is seen at the distance of 1 kilometer under the angle of 1 division, approximately. So if you see a tank whose height is 3 meters under the angle of 2 divisions, the distance is (3/2) times 1000=1500 meters, very simple for quick calculation in your head:-) But the precision instruments were also graded in "divisions" to avoid confusion. Confusion however occured in the interaction with our aviation where the angles were naturally measured in degrees... or with the navy where the distances were measured in cables and miles but the angles still in degrees:-) Grades were also used somewhere in the military but I don't remember where:-) But speaking seriously, probably one reason why the system based on 60 still holds is that 6 is close to 2pi. Closer than 10 anyway:-) Is there anything similar to the Soviet "division" in the West? Alex.