148.—A Home-made Telephone Transmitter. ...................... Fig. 149.—A Complete Telephone Instrument. Two Instruments such as this are necessary to form a simple Telephone System. ............. Fig. 150.—Diagram of Connection for the Telephone Instrument shown in Fig. 149. ...................................................... Fig. 151.—A Desk-Stand Type of Telephone. ......................... Fig. 152.—A Telephone Induction Coil. ............................. Fig. 153.—Diagram of Connection for a Telephone System employing an Induction Coil at each Station. ................................... Fig. 154.—Details of Various Parts of a Medical Coil. ............. Fig. 155.—Details of Interrupter for Medical Coil. ................ Fig. 156.—Completed Medical Coil. ................................. Fig. 157.—Diagram showing Essential Parts of Induction Coil. ...... Fig. 158.—Empty Paper Tube, and Tube filled with Core Wire preparatory to winding on the Primary. ............................ Fig. 159.—Illustrating the Various Steps in winding on the Primary and fastening the Ends of the Wire. ............................... Fig. 160.—Complete Primary Winding and Core. ...................... Fig. 161.—The Primary covered with Insulating Layer of Paper ready for the Secondary. ................................................ Fig. 162.—Simple Winding Device for winding the Secondary. ........ Fig. 163.—Completed Secondary Winding. ............................ Fig. 164.—Interrupter Parts. ...................................... Fig. 165.—Condenser. .............................................. Fig. 166.—Completed Coil. ......................................... Fig. 167.—Diagram showing how to connect the Apparatus for the "Electric Hands" Experiment. ...................................... Fig. 168.—Geissler Tubes. ......................................... Fig. 169.—The Bulb will emit a Peculiar Greenish Light. ........... Fig. 170.—An Electrified Garbage-can. ............................. Fig. 171.—Jacob’s Ladder. ......................................... Fig. 172.—An X-Ray Tube. .......................................... Fig. 173.—Fluoroscope. ............................................ Fig. 174.—How to connect an X-Ray Tube to a Spark-Coil. ........... An X-Ray Photograph of the hand taken with the Outfit shown in Figure 174. The arrows point to injuries to the bone of the third finger near the middle Joint Resulting in a Stiff Joint. .......... Fig. 175.—Comparison between Electric Current and Flow of Water. .. Fig. 176.—Alternating Current System for Light and Power. ......... Fig. 177.—Motor Generator Set for changing Alternating Current to Direct Current. ................................................... Fig. 178.—Step-Up Transformer. .................................... Fig.