Modern Use
Although the unit knot does not fit within the primary SI system, its retention for nautical and aviation use is important because standard nautical charts are on the Mercator projection and the scale varies with latitude. On a chart of the North Atlantic, the scale varies by a factor of two from Florida to Greenland. A single graphic scale, of the sort on many maps, would therefore be useless on such a chart. Since the length of a nautical mile is, for practical purposes, identical to a minute of latitude, a distance in nautical miles on a chart can easily be measured by using dividers and the latitude scales on the sides of the chart.
Speed is sometimes incorrectly expressed as "knots per hour", which would actually be a measure of acceleration, as in "nautical miles per hour per hour".
Read more about this topic: Knot (unit)
Famous quotes containing the word modern:
“The way in which modern German poetry follows theories reminds me of pupils who, scolded by their teacher for their insubordination, justify themselves by saying that they invented new rules of propriety according to which they are quite well- behaved.”
—Franz Grillparzer (1791–1872)
“A modern democracy is a tyranny whose borders are undefined; one discovers how far one can go only by traveling in a straight line until one is stopped.”
—Norman Mailer (b. 1923)