Fig. 25.--Kinds of Aerial Switches

Fig. 26.--Wiring Diagram for a Complete Sending and Receiving Set No. 1

Fig. 27.--Wiring Diagram for Complete Sending and Receiving Set No. 2

Fig. 28.--Water Analogue for Electric Pressure

Fig. 29.--Water Analogues for Direct and Alternating Currents

Fig. 30.--How the Ammeter and Voltmeter are Used

Fig. 31.--Water Valve Analogue of Electric Resistance

(A) and (B) Fig. 32.--How an Electric Current is Changed into Magnetic
Lines of Force and These into an Electric Current

(C) and (D) Fig. 32.--How an Electric Current Sets up a Magnetic Field

Fig. 33.--The Effect of Resistance on the Discharge of an Electric
Current

Fig. 34.--Damped and Sustained Mechanical Vibrations

Fig. 35.--Damped and Sustained Electric Oscillations

Fig. 36.--Sound Wave and Electric Wave Tuned Senders and Receptors

Fig. 37.--Two Electrode Vacuum Tube Detectors