(a) Fig. 106 represents a small, practical apparatus by Salomon. It is designed to open and close a circuit successively by one and the same manoeuvre, and is particularly applicable to the lighting and extinguishing of lamps or to continuous electric bells. It has the appearance and dimensions of the button of an ordinary electric bell. The mechanism comprises an 8-toothed ratchet wheel carrying 4 pins. The button itself carries a pin that extends to the teeth of the ratchet wheel. Every time the button is pressed, the ratchet wheel advances one tooth, from left to right, and makes 1/8 revolution. Under the button is a spiral spring that has the effect of pushing it out as soon as the pressure is removed - the ratchet wheel keeping the position that it has obtained. The 4 pins, through the revolution of the ratchet wheel, press in succession against a horizontal strip of brass, forming a spring that alternately opens and closes the circuit, according as one of the pins is or is not opposite the slightly curved part of the strip. Fig. 106 represents the button in the open circuit position.
To prevent the ratchet wheel from moving backward, a second flat spring engages with each tooth and holds it in place.
(6) An elegant device has been got up by Grangier, of Dinard, for the purpose of lighting or extinguishing a lamp at a distance, from any number of points, by the sole aid of a button and two vires. The principle of it is very simple. It consists in actuating the electro magnet of a relay commutator by pressing upon one of these buttons. The motion of the armature revolves a ratchet wheel 1/8 revolution at each manoeuvre. This revolution is utilised for effecting contacts through the aid of two springs that press against friction rollers provided with parts that art successively insulating and conducting, thus effecting an opening and closing of the circuit connected with the two springs.
(c) The object of this apparatus, Fig. 107, also by Salomon, is to permit of effecting, in a certain measure, a nearly constant lighting by Leclanche piles, through a method of automatic substitution of several series operating one after the other, and depolarising themselves during the period of rest. The apparatus, when once wound up, gives 2700 commutations upon the revolving cylinder, and which come successively into contact with springs, 2, 3, i, 5, 6, 7, that communicate with the positive poles of the different batteries, the negative poles being connected with a common return
In order thai the commutator may not work while the piles are not operating, an electro-magnet is placed beneath the revolving cylinder. As long as the lamps are out, the clock-work movement is locked; but as soon as the lamps are lighted, the electro-magnet attracts its armature, which throws the clock-work movement into gear, and the purely mechanical function of the commutator can then be produced. According to Salomon, it would require 6 batteries of a special model to secure a continuous lighting of indefinite duration, at the rate of 1 ampere, 1.5 volt per element, in making commutations every 30 seconds, thus leaving 150 seconds of rest between two successive periods of work.
Salomon's commutator, by means of slight modifications, may be utilised with advantage for an analogous service - that of the charging of a series of accumulators through a small number of elements (bichromate or sulphate of copper). The commutator should, say every 1/4 hour, make the charging pile pass automatically from one series to the other, and thus perform, systematically and methodically, a manoeuvre hitherto effected by hand, but quite irregularly.
In his last arrangements of the chlorine pile, Upward uses an apparatus whose function is exactly the same as that of the one just described, but its high price leads us to believe that the Salomon arrangement, slightly modified, would solve the problem in a simpler and more economical manner.