Is it ensure, insure, or assure?
attested by 1885.
Previous to 1883 the methods of measuring time in the United States were so varied and so numerous as to be ludicrous. There were 50 different standards used in the United States, and on one road between New York and Boston, whose actual difference is 12 minutes, there were three distinct standards of time. Even small towns had two different standards one known as "town" or local time and the other "railroad" time.
... At noon on November 18, 1883, there was a general resetting of watches and clocks all over the United States and Canada, and the four great time zones, one hour apart, into which the country was divided came into being. So smoothly did the plan work that the general readjustment was accomplished without great difficulty and it has worked satisfactorily ever since. ["Railroad Trainman," 1909]
time zone |
Any of the 24 divisions of the Earth's surface used to determine the local time for any given locality. Each zone is roughly 15° of longitude in width, with local variations for economic and political convenience. Local time is one hour ahead for each time zone as one travels east and one hour behind for each time zone as one travels west. The International Meridian Conference in 1884 established the prime meridian as the starting point for the 24 zones. See more at International Date Line, standard time.
One of approximately 24 longitudinal divisions of the globe, nominally 15 degrees wide, in which clocks show the same time. Some zones follow the boundaries of states or territories, others differ from neighbouring zones by more or less than one hour.
Computers can be programmed to take into account the time zone each user is working in, which is not necessarily the same as the zone the computer is in.
See also TZ.
a zone on the terrestrial globe that is approximately 15 longitude wide and extends from pole to pole and within which a uniform clock time is used. Time zones are the functional basis of standard time (q.v.).