on 16/10/03 12:45 PM, John S. Ward at [EMAIL PROTECTED] wrote: > I agree that as far as passengers on commercial airlines are concerned, it > makes sense to quote all speeds and distances in km/h and km.
<snip> > It's obvious from the definition of the meter that the French had intended to > replace the NM with the km by using decimal angles for maps and navigation. > In conclusion, the "problem" is not nautical miles: it's the crazy way we > measure angles. > > I wish the world had embraced decimal angles and the 1/100000 day second. > Then kWh and km/h would be directly related to the SI units J and m/s by > simple shifts of the decimal, and the geographic coordinates and grids on > maps would already be tied to kilometers. Dear John Ward, Bruce Hebbard and All, It is interesting to consider the decisions of the originators of the metric system in the political and technological contexts of their times. For example, the political forces of the late 18th century were about the development of Empire by several European states, and the technology that went with that was the development of sailing ships and the technology to navigate them rapidly (and safely) around the world. It was within these contexts that Gabriel Mouton, in 1670, made his suggestion that a decimal unit measuring system should be based on a quadrant of the Earth. He suggested that this could also become a standard for measuring all distances. Mouton also encouraged the use of Simon Stevin�s 1585 system of tenths should to divide the units into smaller parts. However this was of lesser concern to Mouton than the issue of the Earth's quadrant. With hindsight, we can see that the very first unit of the Syst�me International d'Unit�s was the quadrant. This fact is more or less universally ignored these days. There are a few people around who are thinking about a better way of measuring angles. For example, Marcus Berger is working on a system that uses a quadrant and divides it into 100 grads (or gons), and Brij Bhushan is working to redefine the second and subsequently the metre to fit into time constraints. I also have developed a model of plane angle measurement that, I think, is better than the present mishmash of degrees, minutes, and seconds. My model goes back to Mouton's original selection of the quadrant as the basic unit of angle measurement. For ease I call this an angle of one 'quad', which has the advantages of being fairly common in the world's languages as the measure of a 'right angle'; it is also a single syllable word that works well with SI's prefixes. For convenience and for most uses, I divide a quad into milliquads. As a matter of interest, a milliquad represents 10 kilometres on any great circle route by a ship or an aircraft, and to be within 10 kilometres of an airport puts you well within the range of radar and other local navigational aids. Cheers, Pat Naughtin LCAMS Geelong, Australia --
