Modern Electric Time Service. 49

1910.] HOPE-JONES : MODERN ELECTRIC TIME SERVICE. 49 MODERN ELECTRIC TIME SERVICE. By F. HOPE-JONES, Member. (Paper received December 2, 1909, and read in London on February 17, 1910.) When I read a paper * before this Institution just ten years ago, electric clocks were at a very low ebb in this country. Towards the end of last century we had all been too busy with the more pressing problems of light and power to make any serious attempt .to apply electricity to horology. The brief review then given showed that practically all the work of English inventors, including even that of Bain and Wheatstone, had been futile, the only survivals of the Victorian Era being the two forms of synchronisation, the Ritchie sympathetic pendulum, and the Lund minute hand clip, both of them necessarily very limited in their applications, while every attempt to introduce foreign systems had failed. This was the position on the threshold of the present century when I introduced the " Synchronome " system to your notice. Some one had to prove that electric clocks, if constructed on sound principles, would work, and for five years it was left to me to do so. In that period three hundred or four hundred installations were erected, and these restored confidence and attracted others into the field. In 1905 no less than five systems sprang into active competition, and the business of electric time service which could hardly be established by one firm alone, however successful, was fairly launched as a branch of our profession. The Council have consequently considered the subject worthy of an Institution evening, but I have now the rather more delicate task of describing the systems of others as well as the latest improvements in my own. Representatives of these systems have, however, been invited here to-night, and I shall make my reading short so that they may make up in the discussion for any deficiency in my recital of their merits. It is practically impossible for me to do justice to other systems in a manner that would satisfy the inventors. In the first place, we have not time, and in the second, my sources of information are limited to what is published in their Patents and printed matter. I must first remind you of the three classes into which the subject is divided :— I. Self-wound clocks, independent of one another, which simply use electricity to provide their motive power. * 'Journal, Institution of Electiical Engineers, vol. 29, p, 119, 1900, VOL. 45. 4 50 HOPE-JONES: MODERN ELECTRIC [Feb. 17th, II. Synchronising systems, in which a regulator or standard clock sends out electrical impulses to correct the hands of complete clocks having an independent life of their own. III. Circuits of electrical impulse dials, in which a controller master clock, or transmitter, whether self-wound or key- wound, sends out electrical impulses at short intervals— e.g., every half-minute or minute—to propel the hands of "receiver," "indicator," or "secondary" dials. The first division does not come within the title of this paper, because it does nothing to strike at the root of the evil—the independence of clocks. It is true that a consulting electrical engineer only last year actually included in a county asylum specification thirty independent non-synchronised self-wound clocks, but we must pass him by for want of time to go over the old ground of collectivism versus individualism in clocks. That mistake is not likely to be made again. Yet there is such a subtle fascination about a self-wound clock that I have obtained specimens of nine of the best and set them going on the table. They are as follows : Hipp, Scott, Aron, Hoeft Miiller, Synchronome, Reason, Eureka, Fery, and Self-Winding Clock Company, of Brooklyn, U.S.A. Automatic time switches for switching on and off electric light at pre- arranged times are usually isolated and cannot be grouped into time circuits. Their independence is therefore justified, and as accurate time-keeping is not necessary it is high time they were made self- winding by one of these methods, and that of the Reason Company was designed for the purpose. The Self-Winding Clock Company, of Brooklyn, U.S.A., comes within my classification because it is always fitted with a synchronising device, but I described that fully ten years ago, and nothing of importance in synchronisation has been achieved since then. I refrain from discussing applications of wireless telegraphy and pass on to— Class III. Circuits of electrically-propelled dials. The systems of electrical impulse dials which are of commercial importance to-day and which practically arrived in the year 1905 are those of Lowne, Aron, Perret, Magneta, and Gent. The systems of Campiche and Palmer (both of which arrived in that year also) are omitted because the amount of wor.k yet done by them is hardly enough to justify their inclusion, but they should be mentioned because they were the first to give impulse to the pendulum in one substantial thrust every half-minute and to rotate a count wheel by the pendulum for that purpose, a method adopted by Lowne, "Synchronome," and Gent, and likely to be generally followed. The time transmitter of Messrs. R. M. Lowne & Son, of Catford, is shown in Fig. 1. The pivoted crutch A (the pins at the bottom of which embrace the pendulum rod) has an extension at the top which carries the escapement rod B. The armature C is held up normally off the poles of the magnet by the flat steel spring E through the medium of the rod D. A pivoted catch lever is seen at F, and a gathering click 1910,] TIME SERVICE. 51 at G, which revolves wheel H once a minute, bringing one end of the lever J every half-minute into the position shown where it will fotm an obstruction in the path of the contact springs K mounted on the crutch A and swinging with the pendulum. The contact L being also normally closed, the magnet is energised on each fifteenth excursion to the left of the seconds pendulum, and power is restored in spring E. FIG. I. The series circuit includes the dials M, M, M1, which are of the simple one-wheel step-by-stcp type similar to that described in my last paper, but provided with shunt coils N. The armature C, when it is thus pulled down, is caught by F, which holds it there until the pendulum on its next swing to the right releases it and allows the spring E to dis- charge itself into the pendulum through the medium of the escapement rod B. 52 HOPE-JONES: MODERN ELECTRIC [Feb.. 17th, A flywheel P is linked to the armature of the pendulum movement to slow its motion in order to make sure that contact L remains closed until the most sluggish dial has operated. The shunt coils N in the dials, by cutting out the resistance of each magnet as soon as it has operated, increase the current through those that require more, and thus it can be truly said that the current consumption is exactly that which the dials require. As an alternative to the inertia device P to prolong the duration of the contact L, two subsidiary transmitters may be used on the alternate circuit system where one makes and the other breaks. This is an elaboration of the electrical interlocking system described in my last paper, and it involves a device for halving the number of vibrations of the armature lever. Though the propulsion of the pendulum might not satisfy the purists in that the pe:idulum is never absolutely free, that it does work at the end of its swing, and that all the energy for contact making is derived from it, it is nevertheless no surprise to me to hear of its excellent time-keeping performances as the details are. of fine design and workmanship. The Aron system is, of course, based upon Dr. Hermann Aron's self- winding action long successfully used in the meters of the Aron Electricity Meter Company, Ltd. It is illustrated in Fig. 2, in which the driving click A, mounted on the armature B, drives the main wheel of the clock by means of the spring C. The carrier D, with insulated blade E and contact blade F, is in a state of unstable equilibrium, and is adapted to be flung in one direction or another by the spring G when the contact pin H on the armature has moved it past the dead centre. It is used to self-wind what may be described as an ordinary striking clock in which the striking part has the sole duty of turning a com- mutator every minute, sending an impulse to the dials and reversing the polarity of the battery every time. In this respect they follow standard German practice which, in such systems as Grau-Wagner, of Wiesbaden, has entirely justified itself. All attempts to produce systems with uni-directional impulses were abandoned on the Continent long ago, because they could not produce contacts perfectly clean and precise in make and break. Possibly they did not realise this as the real reason why their dials did not keep step, but they have been faithful to polarised dial movements for forty years in Germany for the sake of the security which they give. Every impulse might consist of a whole group of untidy splashes instead of a smooth-topped wave without a single polarised dial movement getting out of step.

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