The 24-o'clock system has always been in use for scientific purposes where exactness is required. The manifest and growing objections to the present division of the day into halves and twelfths, for travelers and in the making and interpretation of time-tables, has led to many attempts to improve the system by the adoption of a more convenient method. Without going into the consideration of the merits of the different plans that have been proposed, it will at once be acknowledged that any improvement, to practically succeed in general use, must be simple, and contain no radical departure from the established custom. Such is the 24 o'clock plan, which is gradually and quietly making its way into general use.

The day is only a local phenomenon. Time is only accurately determined by the motions of the planets. The natural divisions determined by these are the year, month, and day. Taking the mean solar day for the standard, or unit, and midnight on some fixed degree of longitude on the earth, as that of Greenwich, for the starting-point, if the earth is divided around its circumference into 24 parts, corresponding to the 24 hours of the day, an absolute standard of time for the whole world is secured, and this is called Kosmic time.

By this arrangement the earth itself becomes the great standard chronometer for all mankind, and in its daily rotations the sun at any point will be the index of Kosmic time. For example: when the seventeenth-hour meridian, which governs the local time of New York or Boston, is under the sun, it is 17 o'clock, Kosmic time; when the eighteenth-hour meridian, which governs the local time of Chicago, is under the sun, it is 18 o'clock ; when the nineteenth-hour meridian, which governs the local time of Denver, it is 19 o'clock; when the twentieth-hour meridian, which governs the local time of San Francisco, is under the sun, it is 20 o'clock Kosmic time; and so on, all around the earth.

Kosmic time indicates universal time, based on the prime meridian, which is Greenwich. Each of the 24 meridians into which the earth is divided then becomes in time just 1 hour apart, as astronomers divide the heavens. It becomes then the time of the universe, the one measure of motion. Its hours are counted from 1 to 24 by meridians of longitude around the earth, passing in succession under the sun. These meridians are standards for local time.

The only change from the present method of reckoning involved in the use of this standard is to count the hours from 1 to 24, instead of from 1 to 12 twice each day. The advantages in simplicity and accuracy are obvious. How to introduce this change practically, in clocks and watches, was the only problem to solve. The construction and operation of the Kosmic dial is as follows: A series of radial spindles, loosely journalled at both ends, Fig. 1, carry numeral blocks and turnstiles. The numerals are so arranged as to appear in their proper order when the blocks are turned. The disk, mounted on the hub of the hour-hand, keeps the numeral blocks in line with the face-plate. It has a notch in its circumference with a projecting pin, which passes through each turnstile in succession once in 12 hours, thus turning the spindles, with their numeral blocks, one-fourth of a revolution.

The power required is infinitesimal, and is taken direct from the central power of the time-piece.

The Kosmic dial is the only method by which local and Kosmic time can be shown simultaneously on a dial of 12 divisions. The regular hour-hand indicates local time; the small hour-hand indicates Kosmic time.

The railway companies of North America adopted this system as the basis of standard time in November, 1883, and now decidedly approve of its practical application to their time-tables and to the dials of clocks and watches.

It is now in use on the Intercolonial Railway, for certain through trains on the Canadian Pacific, and its adoption is extending to other railroads. A report favorable to the adoption of this standard was made by a committee of the American Society of Civil Engineers, of which Mr. SANDFORD FLEMING, who has for eight or nine years taken an active interest in advancing the new reform, was a member.

The meridian of Greenwich, England, was established as the Prime Meridian for longitude, and a "universal day," beginning for all the world at Greenwich, midnight, with the hours numbered in a single series from 1 to 24, was adopted by the leading nations of the world, in a conference at Washington, in October, 1884.

Among the many efforts made by clock and watch manufacturers and others, the Kosmic dial alone interprets the system with the least possible mental and mechanical friction.

It does not change the general appearance and time mechanism of clocks and watches. A procession of Roman numerals from I to XII, followed automatically by a like procession of Arabic numerals from 13 to 24, the two sets taking their places in orderly and unvarying succession, presents to the public eye, in its simplest and clearest expression, precisely the information needed at any hour of the day or night. The removal or insertion of the pin that changes the figures gives the choice between the old and the new systems in a single time-piece.

It is said that about 4,000,000 clocks and watches are manufactured annually, in the United States. To change either the time or mechanism or even the general appearance of clocks and watches, would be a herculean task. This is not at all necessary with the new standard. Any clock or watch can be readily fitted with the new dials, and the relative positions of the numerals in present use are not changed.

Among those working to bring this standard into general adoption are, besides Mr. FLEMING, Mr. W. F. ALLEN, editor of the "Traveller's Official Railway Guide," Prof. CHARLES F. DOWD, Mr. JOHN SWAN, and Mr. HENRY E. WAITE of Boston. Clocks, provided with the turning figures will soon he manufactured for the market, and sample clocks have already been made in considerable variety. It is intended to provide the Boston Post Office with one of these clocks, made in the shape of a globe and hung in Post Office Square, for the better education of the public.

Figs. 3, 4, and 5 show ancient time-keepers; Fig. 6, is the great mean solar standard clock, the time regulator of the world; and Fig. 7, the plan by which the earth itself becomes the standard of time.