Technical World Magazine, May, 1913, pages 428-429:
WIRELESS TIME SERVICE
BELOIT COLLEGE is about to institute, within a radius of one hundred miles of Beloit, a wireless correct time service, based upon observations of the stars. The plan has been in operation for four months in the town of Beloit, and the reports of a newspaper and several manufacturing plants have led to the extension of the service from a scientific experiment to a community service.
Anyone within that territory, who is equipped with an ordinary wireless receiving apparatus, can, of course, get the information.
Owing to the rotation of the earth upon its axis, certain stars, whose positions are definitely known, can be seen to cross the heavens at night, just as the sun seems to cross the sky in the daylight. It is, therefore, possible to determine to the hundredth part of a second, just when these stars should cross the meridian; and through a two and one-half inch transit telescope, set up at the observatory, whose line of light sweeps along a north and south line of the sky, to watch these stars as they approach the meridian. Since it is known at just what time the star under observation should cross the meridian, represented in the lens of the transit, by a threadlike line, it is possible to determine, just as the star crosses the thread in the vision, exactly what time it is.
The record of this time is made on a chronograph, or a time writer, equipped with a moving pen, electrically connected with a large astronomical clock, and a brass cylinder, covered with graph paper, upon which, at regular intervals, with the tick of each second by the astronomical clock, the pen makes a break in the line. This is the record of the clock itself. This pen is also telegraphically connected with an instrument in the hands of the observer at the transit, who causes it to make a fresh, additional break in the line, just as the star under observation crosses the meridian. After identifying the various marks upon the paper, it is possible to compute to one hundredth part of a second, just what time the observer made the additional break in the line of the pen. From the star's known position the precise instant, that the star crossed the meridian, is known. Hence, if the mark of the pen, when operated by the astronomical clock, coincided with the mark made by the observer at the transit, the clock is correct. If not, mathematical computations are at hand to rectify the difference, and the astronomical or "star" clock is set, right to the instant according to star time. The standard time clock, whose mathematical relation to the astronomical clock is known, is then adjusted, correct to the hundredth part of a second. This adjustment occurs daily, the observation weekly.
The standard time clock is connected with a wireless, radio-transmitting station in the science building, several hundred yards across the campus, which is equipped with an aerial four hundred feet long. Precisely at three o'clock every day, the standard time clock, which is connected directly with the aerial, sends out a group of electric waves, through the aid of the transmitting devices, and this group is heard at the receiving station of the patrons, as a single tick, the prearranged signal.
The National Government of France, from the Eiffel Tower, has given such a service for several years.