OF DEXISON UNIVERSnv. ,y 



battery to any one of a great number of combinations. The instru- 

 ment illustrated is adapted to control a battery of twelve, twenty-four, 

 or some multiple of twelve cells. 



It consists of a base a, of thoroughly seasoned wood or ebonite, 

 upon which is fixed a double row of flat, rectangular pieces of brass, 

 I, 2, 3, etc., each two or three centimetres long, one centimetre wide 

 and one half centimetre thick. Each is fi.xed to the base by two 

 round-headed machine screws, d and e, which fit into holes bored 

 nearly through the brass from the under side and tapped out to fit the 

 screws The plates are so placed that the spaces between the rows arc 

 of the same width as the spaces between single plates. All are of 

 equal size except two, 12 and 13, at opposite ends of the upper and 

 lower rows; these are twice as long as the others. The plates may be 

 connected like the coils of a resistance box, by flat plugs of brass 

 shown in end and side elevation at b, and r, F^:^. 2. Binding screws 

 are soldered on at that end of each row which terminates in a short 

 piece of brass. From these wires lead current to any des'red point. 

 Each plate in the upper row is connected to the positive terminal of a 

 battery of one or more cells and each corresponding plate in the lower 

 row with the negative terminal of the same battery. Thus, jjlates i 

 and 13 form the terminals of one battery, and 2 and 14 of another. 

 The battery wires are firmly held by one of the two .screws of each 

 plate, as shown at/. It is well to glue strips of wood, ,1; g, under the 

 ends of the base so that the screw heads will not have to be counter 

 sunk. To show how connections are made, suppo.se the sim])le case 

 where each brass plate is the terminal of a single battery cell. In fij^. 

 3 we see at a, how the plugs must be inserted to give an arrangement 

 of twelve cells in series, at 6 the arrangement of twelve cells parallel, 

 at c, the combination of six cells in series and two parallel, and at J, 

 of three cells in series and two parallel. If the cells are of the Leclanche 

 type, each with an electromotive force of 1.4 volts and internal resist- 

 ance .7 ohm, we would have in the several combinations 



This table shows the range of power possible by a moment's ad 



