........................................... FIG 51.—A Cast Electrode will last much longer than one cut from Sheet Metal. Cast Electrodes like that above are on the market and can be purchased very reasonably. ................................. FIG. 52.—A completed single Cell Rectifier. The right hand sketch shows how the Electrodes are mounted on the underside of the cover. FIG. 53.—A Diagram showing how a Rectifier cuts off one-half of the Alternating Current Wave and changes it into Pulsating Direct Current. .......................................................... FIG. 54.—Circuit showing how a Single Cell of Rectifier should be connected in series with a Lamp Bank to Recharge a Storage Cell. A is the Aluminum Plate and L the Lead or Iron Plate. ............... FIG. 55.—Diagram showing the Difference in Current after it has been passed through a Single Cell or Rectifier and after passing through a Four-Cell Rectifier. ............................................ FIG. 56.—Diagram showing how a Four-Cell Rectifier is connected. The Alternating Current Source is connected to C and D. The Direct Current is taken off at A and B. The Electrodes marked A, A, A, A are the Aluminum Electrodes. L, L, L, L may be Lead or Iron. ...... FIG. 57—A Complete Four-Cell Rectifier connected together and Mounted in a Tray. ................................................ FIG. 58.—Details of the two different Pieces of Sheet Iron used in building up the Core. Sufficient of each piece are required to form a pile of each three-quarters of an inch thick. ................... FIG. 59.—The Method used in piling up the Strips to Assemble the Core. ............................................................. FIG. 60.—Assembly of the Core. .................................... FIG. 61.—Details of the Primary and Secondary Windings. ........... FIG. 62.—Showing the Core completely assembled with the Primary and Secondary in position. P, P are the Primary Terminals. 1, 2 and 3 are the Secondary Terminals. ...................................... FIG. 63.—The Step-down Transformer mounted on a Wooden Base. ...... FIG. 64.—A detailed Drawing showing how the Sides of the Case are formed by bending a long strip of Sheet Iron at four points. ...... FIG. 65.—Details of the Top and Bottom of the Case. ............... FIG. 66.—The completed Transformer. ............................... FIG. 67.—A Simple Galvanometer. ................................... FIG. 68.—Details of the Bobbin. ................................... FIG. 69.—Details of the Armature, Bearings and Pointer. ........... FIG. 70.—A complete Voltmeter having the Scale at the top. ........ FIG. 71—An Ammeter so constructed that the Scale is at the bottom. . FIG. 72.—Showing how the Armature, Shaft and Pointer are assembled