TIME, STANDARD. The time in common use for regulating the ordinary affairs of life. It is derived from the sun. Leaving out of account small irregularities of the solar motion that are of no consequence for our present purpose, when that celestial body is on the meridian of any place we call the time at that place 'noon' or twelve o'clock. (See EQUATION OF TIME.) It follows that when it is noon at any given place it is similarly noon at all other places having the same meridian, and at places baying a different meridian it is either forenoon or afternoon. In fact, as the sun rises in the east and sets in the west, it is evident that when it is crossing the meridian of any place it must have already passed that of neighboring places to the eastward, and not yet have reached that of neighboring places to the westward. In other words, when it is noon in the given place it is already afternoon in places to the eastward, and still forenoon in places to the westward. The farther east one travels, the later is the local time; and this gives rise to the rather perplexing time differ ences so familiar to travelers.
In the ease of railroads this matter of time differences has caused especially confusing com plications. It was formerly customary for a road to use throughout large sections of its ter ritory the local time of one of the principal cities through which it passed. The result was that when railroads met in sonic smaller town, it happened not infrequently that they wel'e running under widely different time systems. As ninny as five different kinds of time have been thus simultaneously in use in a single town.
It was the need of an international standard of time that led to the Prime Meridian Confer ence (q.v.) at Washington, 1882. This recom mended the use of the Greenwich civil time, reckoned from zero up to 24 hours. In accord ance with this resolution, and to remedy the difficulty mentioned above, the United States and Canada selected a series of standard meridians, differing in longitude from that of Greenwich, England, by exact multiples of 15°. October 18,
1S83, a convention was called by W. F. Allen, Secretary of the General Railway Time Con vention, which decided on the introduction of standard time to take effect November 18, 1883, and on that day the change was made without any difficulty.
Now- 15° of longitude corresponds exactly to one hour of time difference, and therefore the local times of the several standard meridians differ from Greenwich by an even number of hours without fractional minutes and seconds. In the United States the standard time merid ians are those whose longitudes are west of Greenwich 60°, 75°, 90°, 105°, and 120°. The Hines of these meridians are respectively 4 hours, 5 hours, 6 hours, 7 hours, andS hours earlier than Greenwich time, because the sun, in travel ing across the sky from east to west, passes the Greenwich meridian before it reaches the Ameri can meridians. The time of the 60th meridian is called Colonial, that of the 75th meridian Eastern, that of thl,1 90th Central, that of the 105th Mountain, and that of the 120th Pacific time. The limiting lines of the time-zones have been so drawn arbitrarily that they never divide any town. Where such a division is theoretically unavoidable, the dividing line for actual use is drawn on the map with a crook in it, so as to put the whole town on one side of the line.
The resolutions of the Washington Conference were not so favorably received on the Continent. The introduction of the time of the 15th merid ian east of Greenwich for the Austrian railways was proposed by Schram in 1881i. In 1889 the matter was brought before the 6e rim n Railway Union and the German Reichstag. Ilylgium and Holland were, however, the first Continental nations to adopt standard time, and other coun tries followed rapidly, as shown in the preced ing table.
BIBLIOGRAPHY. Jacoby, Talks by an AstronoBibliography. Jacoby, Talks by an Astrono- mer (New York, 1902) ; Schram. Mile Actual State of the Standard Time Question," in Ob servatory, vol. iii. (London, 1890).
See DAY; MON TH ; YEAR; INTERNATIONAL DATE LINE; HOROLOGY; CLOCK.