Longitude (book) consults the home port clock, every hour's discrepancy between them translates into another fifteen degrees of longitude. One degree of longitude equals four minutes of time the world over, although in terms of distance, one degree shrinks from 60.15 nautical miles or 111 km [Earth's circumference being: 21,653.521 nautical miles, or 24,901.55 statute miles at the Equator], to virtually nothing at the poles. Precise knowledge of the hour in two different places at once - a longitude prerequisite so easily accessible today from any pair of cheap wristwatches - was utterly unattainable up to and including the era of pendulum
How Many Miles to Babylon? good and your spurs be bright. How mony men have ye? Mae nor ye daur come and see.</poem> Various places have replaced Babylon in the rhyme, including London town, Barberry and Berry Bright. The rhyme was not recorded until the nineteenth century, but the reference to Cantelon in the Scottish version has led some to conclude that it refers to Caledon in the time of the Crusades. Babylon may be a corruption of 'Babyland', but the city was a common allusion particularly in seventeenth-century England and 'Can I get there by candlelight?' was a common saying in the sixteenth century.