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Noon at any place is defined as the moment when either the true or mean sun passes the meridian of that place, according as apparent or mean time is used. Practically, the use of mean time is now universal, so that we may regard the mean sun as that by which noon is determined. As the See also:

earth revolves, all its meridians are brought under the sun in See also:

SUCCESSION (Lat. successio, from succedere, to follow after)

succession or, relative to the earth, noon continually travels around the earth, making the See also:

CIRCUIT (Lat. circuitus, from circum, round, and ire, to go)

circuit in twenty-four See also:

HOURS, CANONICAL

hours. It follows that noon, and therefore any other See also:

HOUR

hour of the See also:

day, is later by four minutes for every degree of See also:

LONGITUDE (from Lat. longitudo, " length ")

longitude towards the See also:

west, so that a See also:

WATCH (in O. Eng. wcecce, a keeping guard or watching, from wacian, to guard, watch, wacan, to wake)

watch carried See also:

east or west will be found to deviate from local time by an amount proportional to the See also:

CHANGE (derived through the Fr. from the Late Lat. cambium, cambiare, to barter; the ultimate derivation is probably from the root which appears in the Gr. «a urmu', to bend)

change of longitude. Before the time of See also:

RAILWAYS

railways this deviation was not productive of inconvenience. But when railway travelling became See also:

COMMON

common, See also:

TRAIN (M. Eng. trayn or trayne, derived through Fr. from Late Lat. trahinare, to drag, draw, Lat. trahere, cf. trail, trace, ultimately from the same source)

train schedules had to be more exact than those of a See also:

MAIL

mail eoach, and the traveller was rapidly carried to places where the local time continually deviated from that shown by his watch. The use of such time thus had to be modified in places where intercommunication with others of a different longitude was frequent. Thus arose a practice on the See also:

PART

part of railways of using the time of some central or important See also:

CITY (through Fr. cite, from Lat. civitas)

city on its See also:

LINE

line for all places not too distant, which time would naturally be adopted by the inhabitants of the region through which itpassed. For a similar See also:

REASON (Lat. ratio, through French raison)

reason, in countries which did not extend through a large fraction of an hour of longitude, it was natural to use the time of the See also:

capital throughout all or a large part of its extent. Thus See also:

GREENWICH

Greenwich time has See also:

long been in use throughout See also:

England, and all the railways of See also:

France are run by See also:

Paris time.

But inconvenience was still unavoidable in passing from one See also:

COUNTRY (from the Mid. Eng. contre or contrie, and O. Fr. cuntree; Late Lat. contrata, showing the derivation from contra, opposite, over against, thus the tract of land which fronts the sight, cf. Ger. Gegend, neighbourhood)

country to another, or in travelling through long stretches in the same country. The inconvenience was especially See also:

FELT (cognate with Ger. Filz, Du. vilt, Swed. and Dan. fill; the root is unknown; the word has given Med. Lat. filtrum, " filter ")

felt in the See also:

UNITED

United States, where every railway, and even every long stretch of several See also:

GREAT

great railways, had its own time See also:

SYSTEM

system. Thus it happened not infrequently that in a single station clocks would be found set to the time of three different meridians, one for the road toward the east, another for the road toward the west, and a third for the meridian of the place, or local use. A See also:

DEVICE

device now being generally adopted to do away with this confusion was planned in 1878–1879 by Mr (afterwards See also:

Sir) See also:

SANDFORD, JOHN DE (d. 1294)

Sandford See also:

Fleming, and published in the See also:

Journal of the See also:

CANADIAN

Canadian See also:

INSTITUTE (from Lat. instituere, to establish or set up)

Institute of See also:

TORONTO

Toronto for 1879. On the initiative of this organization, Mr Fleming's proposals were officially communicated to the leading governments of the See also:

WORLD

world with a view of securing an See also:

INTERNATIONAL, THE

international unification of the method of designating the. hour of the day for common use. Naturally connected with the proposal was that of a See also:

PRIME, PRIMER AND PRIMING

prime meridian, from which all longitudes should be reckoned. United States invited an international See also:

CONFERENCE

conference, which was held in See also:

Washington in 1884, for the purpose of proposing a standard meridian to which longitudes and times should be referred. Before this conference was called the railway managers of the United States, after long: discussion, adopted the system. Its fundamental See also:

IDEA (Gr. Ibia, connected with i&eiv, to see; cf. Lat. species from specere, to look at)

idea was that twenty-four standard meridians should be established 15° apart in longitude, starting from the meridian of Greenwich and extending See also:

ROUND (O. Fr. rond, Lat. rotundus, the Fr. is the source also of Du. rond; Ger., Swed., Dan. and Nor. rond)

round the globe. Then on each meridian the local time would differ from Greenwich time by some entire number of hours. At every point of the globe the time to be adopted for common use was that of the nearest standard meridian. These meridians would therefore See also:

mark the central lines of twenty-four zones, within each of which the time to be adopted would be See also:

UNIFORM

uniform, but which would change by an hour on passing from one See also:

ZONE (Gr. 'WV77, a girdle, from 'wvvLvay to gird)

zone into another.

The inhabitants of each zone naturally use the time of the zone instead of their local time, the maximum difference between the two being See also:

HALF

half an hour. When the system was first established in the United States a delicate legal question arose as to whether the business of See also:

banks and courts should be legally adjusted to the new time. This was soon settled by See also:

state See also:

LAWS

laws making the standard time legal within the limits of each zone. A similar system is being adopted in See also:

EUROPE

Europe, the standard meridians being those of 15°, 30°, &c., east of Greenwich. France, however, still adheres to Paris timel but See also:

Belgium and See also:

Holland use Greenwich time, and See also:

SWITZERLAND

Switzerland, See also:

Italy and central See also:

Germany use the time of 15° E., and therefore one hour in advance of that of Greenwich. This is termed See also:

mid-See also:

EUROPEAN

European time. The system we have described is that adopted for, the purposes of the railways and of• daily See also:

LIFE

life. For scientific and for some international purposes yet other modifications are desirable. An important distinction must be made between the cases in which convenience requires that the time have some relation to the hour of the day, and those where no such relation is required. The former is the See also:

case in designating acts or occurrences which depend upon our daily routine of See also:

REST (O. Eng. rest, reste, bed, cognate with other Teutonic forms, e.g. Ger. Rast, Riiste, rest, and probably Gothic Rasta, league, i.e. resting or stopping place)

rest and wakefulness. But if nothing is necessary except the designation. of some moment. of See also:

ABSOLUTE (Lat. absolvere, to loose, set free)

absolute time, irrespective of our daily routine of life, then only a single measure for the whole world is necessary. At , the Washington Meridian Conference of 1884 it was proposed that Greenwich time should be adopted as a standard for the whole world in all matters of this class, especially in astronomical practice and in See also:

cable despatches.

But this system does not seem to have been extensively adopted outside of See also:

ASTRONOMY (from Gr. &arpov, a star, and v ,usiv, to classify or arrange)

astronomy, the I A See also:

BILL

bill adopting Greenwich time in ' France, which had already See also:

SEED (from the root seen in Lat. serere, to sow)

seed the Chamber of Deputies, was favourably reported on in the Hate in See also:

DECEMBER (Lat. decent, ten)

December, 1910. 988 cultivators of which are most accustomed to the See also:

CONVERSION (Lat. conversio, from convertere, to turn or ,change)

conversion of local into standard or Greenwich time. An unavoidable inconvenience associated with the system is the uncertainty in many cases whether local or Greenwich mean time is under-stood. This must be especially the case with magnetic and seismic phenomena, the designation of which should be uniform for the whole earth; at See also:

PRESENT

present, however, we cannot invariably expect local observers to convert their observations from local into Greenwich mean time. Associated with this question is that of the moment when the day should begin, or from which the hours should be counted. The See also:

CIVIL

civil See also:

DIVISION (from Lat. dividere, to break up into parts, separate)

division of the day into a.m. (ante meridiem, before mid-day) and p.m. (See also:

POST

post meridiem, after mid-day), now practically universal in See also:

HOUSEHOLD, ROYAL

household and See also:

ORDINARY (med. Lat. ordinarius, Fr. ordinaire)

ordinary civil life, is impracticable for scientific purposes, where a See also:

COUNT (Lat. comes, gen. comitis, Fr. comte, Ital. conte, Span. conde)

count of the hours from o up to 24 is necessary. In railway schedules the See also:

NECESSITY (Lat. necessitas)

necessity of distinguishing a.m. from p.m. when our civil time is used is found so troublesome that in some countries, especially Italy and See also:

CANADA

Canada, the 24-hour system is used. Hours after noon are there designated as 13, 14, &c., up to midnight, at which moment a new day begins. On the other See also:

hand, with some few exceptions, astronomers have almost from time immemorial begun their day at noon, and navigators have very generally adopted the same practice, but for a quite different reason. In astronomy the day begins at noon for two reasons of convenience.

One is that as the day is fixed by the transit of the sun over the meridian, it is more natural to start the count of the hours from this moment than from that when the sun is on the invisible antimeridian at midnight. This practice also coincides with that of counting the hours of sidereal time from the transit of the vernal See also:

EQUINOX (from the Lat. aequus, equal, and nox, night)

equinox, and leads to the See also:

SIMPLE

simple See also:

RULE

rule that the local mean time is equal to the hour See also:

ANGLE (from the Lat. angulus, a corner, a diminutive, of which the primitive form, angus, does not occur in Latin; cognate are the Lat. angere, to compress into a bend or to strangle, and the Gr. ayKOS, a bend; both connected with the Aryan root ank-, to

angle of the mean sun. The other reason is that, as the astronomer makes most of his observations at See also:

NIGHT

night, and often after midnight, it is inconvenient to begin a new day at the latter hour. This See also:

CONSIDERATION (from Lat. considerare, to look at closely, examine, generally taken to be from con-, and the base seen in sidus, sideris, a star, the word being supposed to be originally an astrological or astronomical term)

consideration is however reversed in day observations, especially those on the sun, but these are few in number. Navigators began the day at noon because their See also:

LATITUDE (Lat. latitudo, latus, broad)

latitude is determined by observations of the sun, while the longitude is also generally determined during the daytime. Thus, in doing the " day's See also:

WORK

work " in the See also:

LOG (a word of uncertain etymological origin,possibly onomatopoeic; the New English Dictionary rejects the derivation from Norwegian lag, a fallen tree)

log, the position of the See also:

SHIP

ship was always computed for noon. Such being the case, it was found more convenient to begin the count of a new day at this hour, to be continued through the night until the following noon. But the navigator's count of days was one day in advance of that of the astronomers; for example, See also:

March the loth, astronomical time, begins on the loth day of March at noon, and this count continues until noon of the day following, so that the forenoon of March the rrth, civil time, is still March the See also:

ROTH, JUSTUS LUDWIG ADOLF (1818-1892)

roth, astronomical time. But the navigator begins March the See also:

firth at noon on March the roth. This difference is worthy of mention because a widespread misapprehension exists that the navigator was forced to count his days from noon owing to the See also:

ADOPTION (Lat. adoptio, for adoptalio, from adoptare, to choose for oneself)

adoption of the same system in the Nautical See also:

ALMANAC

Almanac. The fact is that the practice of the navigator, like that of the astronomer, was adopted purely for his own convenience, and for the reasons just set forth. It is, however, being changed so as to conform to civil time, but as yet no See also:

general See also:

law prescribes the change.

At the Meridian Conference of 1884, it was proposed that the practice of beginning the day at midnight should be adopted universally in astronomy and See also:

NAVIGATION (from Lat. navis, ship, and agere, to move)

navigation, and that the hours should be counted from that moment in all the nautical and astronomical ephemerides. The question of adopting this system became a subject of international See also:

correspondence. The views of the See also:

DIRECTORS

directors" of the astronomical ephemerides, so far as elicited, were strongly against the change. The considerations which determined them were the confusion which the change would introduce into the tables and the count of time in the ephemerides, including the relation of sidereal and See also:

SOLAR, SOLLER (Lat. solarium, Fr.• galetas, Ital. solaio)

solar time; the unavoidable doubt as to whether the one or the other system was used in astronomical publications; and the danger of placing in the hands of the navigator an See also:

EPHEMERIS (Greek for a " diary ")

ephemeris in whichthe hours should have a different meaning from that to which he was accustomed. On the other hand, the reasons of convenience which led to the practice of beginning the day at noon still continued, so that nothing could be shown to counterbalance these drawbacks Still, in See also:

WORKS

works to be used by the public, especially almanacs an: other astronomical annuals, it is necessary to convert astronomical into civil time. This must continue to be done, but offers no difficulty to the authors of such works, who are acquainted with the difference, nor to the public, which has no See also:

INTEREST

interest in the ephemerides and See also:

MEASURES

measures of time used by the professional astronomer. (S.

End of Article: TIME, STANDARD

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