256 PROCEEDINGS OF THE AMERICAN ACADEMY. . 



the terminals of the cells are made of thick lead wire, which are led 

 through wooden supports far from any possibility of corrosion where 

 they connect to the copper wires of the main circuits. The unit of the 

 battery consists of three test tubes, mounted in holes bored in blocks 

 of wood 5 X 5 X 15 cm. {U, Figs. 1 and 2). These blocks of wood 

 are boiled in parafline, and the tubes are held upright by means of 

 paraffine, which is poured into the holes in which the tubes are inserted, 

 these holes being made slightly larger than the tubes. On solidification 

 the tubes are held upright. There are twenty of such blocks on each 

 shelf of one upright case, thus making sixty cells to a shelf ; and there are 

 seven shelves to a case, making four hundred and twenty cells to a case. 

 On the back of such cases are arranged knife-edge switches, which enable 

 me to arrange the cells in multiple or in series, — to employ one shelf or 

 the entire number. At the extremity of each row of six cases is a switch 

 board with similar switches, which enable me to use one case or any com- 

 bination of the entire number of six cases. These switch boards consist 

 of dry whitewood, the insulation of which has been found to answer per- 

 fectly. Since the practical success of such a large battery depends upon 

 the ease with which the cells can be charged in multiple and discharged 

 in series, I have represented the scheme of connections of two shelves, 

 sixty cells on each case. The remaining cells on successive shelves of 

 each case are connected in a similar manner. A and A' (Fig. 3) repre- 

 sent the terminals of each line of twenty cells. Their lead terminals are 

 led to the back of the case, where there are switches which have pivots 

 at the points E and D. These switches, revolving about the pivots E 

 and D, connect the terminals of the cells to a wire running through the 

 pivots E, and through the points L ; in which case the cells are in mul- 

 tiple. If, however, the points N' and N", are thrown out by revolving 

 the switches about E, and the points L of the switches are connected to 

 N' and N" , the cells are thrown into series. This operation can be 

 quickly accomplished, the points N' and the points N" moving to- 

 gether, and also the points L moving together about the pivots D. In 

 arrangement for series, therefore, the current goes from D to N', then 

 to A, then through the row of twenty cells to A', thence to D, to N', 

 and to A, again to A', and then to the next row of switches correspond- 

 ing to the next shelf, and so on. 



A similar plan of switch boards has been erected for each half of the 

 entire battery, consisting of five thousand cells, in order that one half of 

 the battery may be used, or the entire number of cells. At the ex- 

 perimental table to which the terminals of the battery are led there are 



