Page:Popular Science Monthly Volume 89.djvu/147

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��panel with its wood pieces has been removed and a piece of the second or interior panel broken away to show the ar- rangement of the cellri in the box. It will be seen that the interior of the case is divided into twelve compartments by means of thin fiber strips and at the front of each compart- ment is a pair of contacts against which the electrodes of the battery are forced by the sliding panel at the back of the case. These two con- tacts consist of a switch- point and a spring, the switch-point for making con- tact with the long springlike electrode of the cell and the spring-contact making con- tact with the short, stiff electrode of the cell.

By the diagonal arrangement of the spring-contacts shown, the use of connec- ting wires is obviated and an arrange- ment made whereby all the cells are inserted in the same position. In Fig. 4 these diagonal springs are shown as suspended in mid-air in order to show the method of making contact. The switch-points further act as connections for the leads to the high-tension switch. Between the front panel and the interior contact panel all the connecting wires are neatly placed and well protected. Fig. 5 is a sectional view taken on the line of the testing-lamp and looking toward the left in Fig. i. The arrange- ment of contacts and the connecting space at the back of the switches is here clearly shown. It will be noted that the switch panel with its wood backing forms a cover for the battery holder, and is secured to the latter by means of the large screws shown at the right and left-hand ends of the front panel. On loosening these two ^screws, the cover may be removed and the connections

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���Detail of the top and bottom of the case

��Details of ends of the case, sliding rear panel, front panel, etc.

��examined, yet cells may be inserted from the back at any time without disturbing a single connection.

Fig. 6 is a section taken through the high-tension switch and shows clearly the arrangement of the switch parts.

Fig. 7 is a section through the testing- switch and shows the arrangement of the parts of this switch and also more clearly how the switch arms are normally out of contact with the points.

Consider now the details of con- struction in diagrams on this and fol- lowing page: Detail I is at the top and bottom panels of the case. The narrow transverse slots are for the fiber separa- tors and may be carefully cut with a hack-saw. The slot in which the sliding- back of the case fits is shown at the back and should be made smooth and true. Detail 2 shows the ends of the case, and 3 is the sliding-rear of the case. At its right-hand end a recess should be made to enable this piece to be slid out easily. Detail 4 is at the top and bottom of the cover or switch panel support, while 5 shows the end-pieces of the same. The fiber .separating pieces (6), should be made a rather tight fit in the slots provided for them.

The front panel (7) should be very carefully laid out before being drilled. It may, after drilling, be rubbed down with pumice stone and water to get the dull finish so much desired.

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