In many industries there are operations that have to be repeated at regular intervals, and, for this reason, the construction of an apparatus for giving a signal, not only at the hour fixed, but also at equal intervals, is a matter of interest. The question of doing this has been solved in a very elegant way by Mr. Silas in the invention of the apparatus which we represent in Fig. 1. It consists of a clock whose dial is provided with a series of small pins. The hands are insulated from the case and communicate with one of the poles of a pile contained in the box. The case is connected with the other pole. A small vibrating bell is interposed in the circuit. If it be desired to obtain a signal at a certain hour, the corresponding pin is inserted, and the hand upon touching this closes the circuit, and the bell rings. The bell is likewise inclosed within the box. There are two rows of pins--one of them for hours, and the other for minutes. They are spaced according to requirements. In the model exhibited by the house Breguet, at the Vienna Exhibition, there were 24 pins for minutes and 12 for hours. Fig. 2 gives a section of the dial. It will be seen that the hands are provided at the extremity with a small spring, r, which is itself provided with a small platinum contact, p. The pins also carry a small platinum or silver point, a. In front of the box there will be observed a small commutator, M, (Fig. 1). The use of this is indicated in the diagram (Fig. 3). It will be seen that, according as the plug, B, is introduced into the aperture to the left or right, the bell. S, will operate as an ordinary vibrator, or give but a single stroke.

FIG. 1.--SILAS' CHRONOPHORE.

FIG. 1.--SILAS' CHRONOPHORE.

P is the pile; C is the dial; and A is the commutator.

It is evident that this apparatus will likewise be able to render services in scientific researches and laboratory operations, by sparing the operator the trouble of continually consulting his watch.--La Lumiere Electrique.

FIG. 2.

FIG. 2.

FIG. 3.

FIG. 3.

[THE GARDEN.]