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Encyclopedia entry: nautical mile
- Article from:
- The Oxford Companion to Ships and the Sea
Copyright© The Oxford Companion to Ships and the Sea 2006, originally published by Oxford University Press 2006. (Hide copyright information)
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nautical mile,
the unit of distance used at sea, practically speaking a minute of
latitude
. The publication in London in 1637 of
The Seaman's Practise
by the English surveyor Richard Norwood, who had measured an arc of the
meridian
, effectively marked the distinction between the land mile and the sea mile. ‘There are’, he wrote in his preface, ‘a greater number of feet contained in a degree than the common opinion that a thousand paces (of 5 feet) make a mile.’ If the earth were a perfect sphere, a nautical mile would, of course, measure an arc length of one minute at all places and in all directions; but it is an oblate spheroid so that the nautical ...