At the price named it would be too costly for lighting on the large scale; but there are very many persons who would go to the expense of fitting up the battery and the lamp if they could have a light of 20 candles at a cost of \d. an hour. Possibly before long some one may invent an iron or a lead battery, and then those who are so anxious to have the electric light will probably have an opportunity of gratifying their desires , as, indeed, they may now, if only they are prepared to pay for them. But so long as zinc is used there is small chance of primary batteries supplanting dynamos and steam - engines. (Eng. Mcch.)

Axo

The Axo battery, constructed by the Leclanche Battery Co., of America, is an " improved " form of Leclanche, intended to overcome some of the defects of batteries of the porous cup class. The porous cup has a flange which rests on the rim of the jar and forms of itself a cover for the cell. The zinc passes through an independent aperture of its own in the shoulder of the jar. The carbon conductor has inclined sides, increasing in size from the top to the bottom. By gravitation, therefore, the particles of the surrounding mixture are always in perfect and continuous electrical contact with its surface. The carbon itself is provided with ventilating grooves extending along its sides, by which it is much more readily relieved of the bubbles of gas which form on its surface and retard the electric action, than by the holes usually run through the seal and into the mixture. The well-known lead cap of the carbon is dispensed with, and in its place is used a thimble with thumbscrew, which can be slipped off and replaced in a moment.

The battery wire passes through a small hole in the top of the thimble, and into a recess in. the carbon, against which, it is clamped by the thumbscrew.

Bichromate piles, especially those single liquid ones that are applied to domestic lighting, all present the grave defect of consuming almost as much zinc in open as in closed circuit, and of becoming rapidly exhausted if care be not taken to remove the zinc from the liquid when the battery is not in use. This operation, which is a purely mechanical one, has hitherto required the pile to be located near the place where it was to be used, or to have at one's disposal a system of mechanical transmission that was complicated and not very ornamental. In order to do away with this inconvenience, which is inherent to all bichromate piles, Mareschal has invented and had constructed an ingenious system that consists in suspending the frame that carries all the battery zincs from the extremity of a horizontal beam, and balancing them by means of weights at the other extremity. The system, being balanced, the lifting or immersion of the zincs then only requires a slight mechanical power, such as may be obtained from an ordinary kitchen jack, through a combination that will be readily understood upon reference to Fig. 72a. The axis M of the jack, on revolving, carries along a crank M D, to which is fixed a connecting-rod A, whose other extremity is attached to the horizontal beam that supports the zincs and counterpoises.

If the axle M be given a continuous revolution, it will communicate to the rod A an upward and downward motion that will be transmitted to the beam and produce an alternate immersion and emersion of the zincs.

Upon stopping the jack at certain properly selected positions of the rod MD, the zincs may, at will, be kept immersed in the liquids, or vice versa. This is brought about in the following way: The jack carries along in its motion a horizontal fly-wheel V, against whose rim there bears an iron shoe F, placed opposite an electromagnet E. In the ordinary position, this shoe, which is fixed to a spring, bears against the felly of the wheel and stops the jack through friction. When a current is sent into the electro-magnet E, the brake shoe F is attracted, leaves the fly-wheel, and sets free the jack, which continues to revolve until the current ceases to pass into the electro.

The problem, then, is reduced to sending a current into the electro and in shutting it off at the proper moment. This result is obtained very simply by means of an auxiliary Leclanche pile (the piles got up for house bells will answer). The current from this pile is cut off from the electro F by means of a button B when it is desired to light or extinguish the lamps. In a position of rest, for example, the crank M D is vertical, as shown in the diagram to the right in Fig 72a. The circuit is open between M and N through the effect of the small rod which separates the spring B from the spring R'. As soon as the circuit has been closed, be it only for an in • stant, the crank leaves its vertical position, the rod C quits the bend S, and the spring R, by virtue of its elasticity, touches the spring R', and continues its contact until the crank M D having made a half revolution, the rod C repulses the spring R, and breaks the circuit anew. The brake then acts, and the crank stops after making a revolution of 180° and immersing the zincs to a maximum depth. In order to extinguish the lamp, it is only necessary to press the button B again. The axle M will then make another half revolution, and, when it stops, the zincs will be entirely out of the liquid.

The depth of immersion is regulated by fixing the crank-pin D in the apertures T1 or T2 of the connecting-rod. This permits the travel, and consequently the degree of immersion, to be varied. The device requires three wires, two for connecting the lamp with the battery, and one for manoeuvring the apparatus through a closing of the contact B. With Mareschal's system, bichromate piles may be utilised in a large number of cases where a light of but short duration is required until the battery is exhausted, without the tedious manoeuvring of a winch and without inconvenience. The jack permits of a large number of lightings and extinctions being effected before it becomes necessary to wind up its clockwork movement. This operation, however, is very simple, and may be performed every time the battery is visited in order to see what state it is in. Mareschal's apparatus is an indispensable addition to every case of domestic electric lighting in which bichromate piles are used, and, in general, to all cases where the pile becomes uselessly exhausted in open circuit.