HOW LONG IS <A DAY?

Auckland Star, Volume LIV, Issue 72, 24 March 1923, Page 26

HOW LONG IS <A DAY?

TWEXTYFOUR HOURS XOT THE' USUAL LIMIT. Wo are apt to refer to a day, or a : day and a night, to indicate a specific i period of time, without realising that these terms have a different meaning in: different parts of the world. Xot every- | where and always does the natural day [ include twenty-four hours if measured , from sunrise to sunriee. i The fart is that a day is not a fixed : number of hours, but the length of time j during which the light of the sun illumines any part of the earth, tn some ! parts of Norway the day lasts from May, 21 to July 22 without interruption. : ■Jn Spitzcnbergen the longest day is ; three and one-half months, and the i shortest two and a-half of actual light. I At Petrograd the longest day is nineteen hours, and the shortest five. At Hamburg the longest, is seventeen and j the shortest seven, and in London the ! longest is sixteen and a-half and the: shortest eight. | The beginning of the day is not a i question of universal agreement. It has j beon arbitrarily decided 'by different j people's from time to time. [ The ancient Jews fixed the beginning! of the day at sunrise; with the TJmbriani I it began at noon, and the Egyptians and Romans fixed the time nt midnight, a custom adopted by the United States ani by moat of the European countries. It is a matter of common knowledge; that the longest day of the year is D«-! cembcr 21, and the shortest June 21. j This latter is the time w':;en s-.in | is farthest north on its annual slant, over the tropic of Cancer, makinj the maximum declination to the axle of the earth. All over the world this date marks a turning point in duration of the day, although in every case it is not the shortest day. In places north of the equator they are enjoying the longest day.