Measuring Instruments. The Detector. Direction of Current. Simple Current Detector. How to Place the Detector. Different Ways to Measure a Current. The Sulphuric Acid Voltameter. The Copper Voltameter. The Galvanoscope Electro-magnetic Method. The Calorimeter. The Light Method. The Preferred Method. How to Make a Sulphuric Acid Voltameter. How to Make a Copper Voltameter. Objections to the Calorimeter. VI. VOLTS, AMPERES, OHMS AND WATTS Page 60 Understanding Terms. Intensity and Quantity. Voltage. Amperage Meaning of Watts and Kilowatt. A Standard of Measurement. The Ampere Standard. The Voltage Standard. The Ohm. Calculating the Voltage. VII. PUSH BUTTONS, SWITCHES, ANNUNCIATORS, BELLS AND LIKE APPARATUS Page 65 Simple Switches. A Two-Pole Switch. Double-Pole Switch. Sliding Switch. Reversing Switch. Push Buttons. Electric Bells. How Made. How Operated. Annunciators. Burglar Alarm. Wire Circuiting. Circuiting System with Two Bells and Push Buttons. The Push Buttons, Annunciators and Bells. Wiring Up a House. VIII. ACCUMULATORS, STORAGE OR SECONDARY BATTERIES Page 82 Storing Up Electricity. The Accumulator. Accumulator Plates. The Grid. The Negative Pole. Connecting Up the Plates. Charging the Cells. The Initial Charge. The Charging Current. IX. THE TELEGRAPH Page 90 Mechanism in Telegraph Circuit. The Sending Key. The Sounder. Connecting Up the Key and Sounder. Two Stations in Circuit. The Double Click. Illustrating the Dot and the Dash. The Morse Telegraph Code. Example in Use. X. HIGH-TENSION APPARATUS, CONDENSERS, ETC. Page 98 Induction. Low and High Tension. Elastic Property of Electricity. The Condenser. Connecting up a Condenser. The Interrupter. Uses of High-tension Coils. XI. WIRELESS TELEGRAPHY Page 104 Telegraphing Without Wires. Surging Character of High-tension Currents. The Coherer. How Made. The Decoherer. The Sending Apparatus. The Receiving Apparatus. How the Circuits are Formed. XII. THE TELEPHONE Page 110 Vibrations. The Acoustic Telephone. Sound Waves. Hearing Electricity. The Diaphragm in a Magnetic Field. A Simple Telephone Circuit. How to Make a Telephone. Telephone Connections. Complete Installation. The Microphone. Light Contact Points. How to Make a Microphone. Microphone, the Father of the Transmitter. Automatic Cut-outs for Telephones. Complete Circuiting with Transmitters. XIII. ELECTROLYSIS, WATER PURIFICATION, ELECTROPLATING Page 123