Electricity for Boys

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

Decomposing Liquids. Making Hydrogen and Oxygen. Purifying Water. Rust. Oxygen as a Purifier. Composition of Water. Common Air Not a Good Purifier. Pure Oxygen a Water Purifier. The Use of Hydrogen in Purification. Aluminum Electrodes. Electric Hand Purifier. Purification and Separation of Metals. Electroplating. Plating Iron with Copper. Direction of Current.

XIV. ELECTRIC HEATING. THERMO-ELECTRICITY Page 135

Generating Heat in a Wire. Resistance of Substances. Signs of Connectors. Comparison of Metals. A Simple Electric Heater. How to Arrange for Quantity of Current Used. An Electric Iron. Thermo-Electricity Converting Heat Directly into Electricity Metals. Electric, Positive, Negative. Thermo-electric Coupler.

XV. ALTERNATING CURRENTS, CHOKING COIL, TRANSFORMER Page 145

Direct Current. Alternating Current. The Magnetic Field. Action of a Magnetized Wire. The Movement of a Current in a Charged Wire. Current Reversing Itself. Self-Induction. Brushes in a Direct Current Dynamo: Alternating, Positive and Negative Poles. How an Alternating Current Dynamo is Made. The Windings. The Armature Wires. Choking Coils. The Transformer. How the Voltage is Determined. Voltage and Amperage in Transformers.

XVI. ELECTRIC LIGHTING Page 161

Early conditions. Fuels. Reversibility of Dynamo. Electric arc. Mechanism to maintain the arc. Resistance coil. Parallel carbons for making arc. Series current. Incandescent system. Multiple circuit. Subdivision of electric light. The filament. The glass bulb. Metallic filaments. Vapor lamps. Directions for improvements. Heat in electric lighting. Curious superstitions concerning electricity. Magnetism. Amber. Discovery of the properties of a magnet. Electricity in mountain regions. Early beliefs as to magnetism and electricity. The lightning rod. Protests against using it. Pliny's explanation of electricity.

XVII. POWER, AND VARIOUS OTHER ELECTRICAL MANIFESTATIONS Page 175

Early beliefs concerning the dynamo. Experiments with magnets. Physical action of dynamo and motor. Electrical influence in windings. Comparing motor and dynamo. How the current acts in a dynamo. Its force in a motor. Loss in power transmission. The four ways in which power is dissipated. Disadvantages of electric power. Its advantages. Transmission of energy. High voltages. The transformer. Step-down transformers. Electric furnaces. Welding by electricity. Merging the particles of the joined ends.

XVIII. X-RAY, RADIUM AND THE LIKE Page 184

The camera and the eye. Actinic rays. Hertzian waves. High-tension apparatus. Vacuum tubes. Character of the ultra-violet rays. How distinguished. The infra-red rays. Their uses. X-rays not capable of reflection. Not subject to refraction. Transmission through opaque substances. Reducing rates of vibration. Radium. Radio-activity. Radio-active materials. Pitchblende. A new form of energy. Electrical source. Healing power. Problems for scientists.

Electricity, like every science, presents two phases to the student, one belonging to a theoretical knowledge, and the other which pertains to the practical application of that knowledge. The boy is directly interested in the practical use which he can make of this wonderful phenomenon in nature.

It is, in reality, the most successful avenue by which he may obtain the theory, for he learns the abstract more readily from concrete examples.

It is an art in which shop practice is a greater educator than can be possible with books. Boys are not, generally, inclined to speculate or theorize on phenomena apart from the work itself; but once put them into contact with the mechanism itself, let them become a living part of it, and they will commence to reason and think for themselves.

It would be a dry, dull and uninteresting thing to tell a boy that electricity can be generated by riveting together two pieces of dissimilar metals, and applying heat to the juncture. But put into his hands the metals, and set him to perform the actual work of riveting the metals together, then wiring up the ends of the metals, heating them, and, with a galvanometer, watching for results, it will at once make him see something in the experiment which never occurred when the abstract theory was propounded.

He will inquire first what metals should be used to get the best results, and finally, he will speculate as to the reasons for the phenomena. When he learns that all metals are positive-negative or negative-positive to each other, he has grasped a new idea in the realm of knowledge, which he unconsciously traces back still further, only to learn that he has entered a field which relates to the constitution of matter itself. As he follows the subject through its various channels he will learn that there is a common source of all things; a manifestation common to all matter, and that all substances in nature are linked together in a most wonderful way.

An impulse must be given to a boy's training. The time is past for the rule-and-rote method. The rule can be learned better by a manual application than by committing a sentence to memory.

In the preparation of this book, therefore, I have made practice and work the predominating factors. It has been my aim to suggest the best form in which to do the things in a practical way, and from that work, as the boy carries it out, to deduce certain laws and develop the principles which underlie them. Wherever it is deemed possible to do so, it is planned to have the boy make these discoveries for himself, so as to encourage him to become a thinker and a reasoner instead of a mere machine.

A boy does not develop into a philosopher or a scientist through being told he must learn the principles of this teaching, or the fundamentals of that school of reasoning. He will unconsciously imbibe the spirit and the willingness if we but place before him the tools by which he may build even the simple machinery that displays the various electrical manifestations.

The Study of Electricity. Historical

There is no study so profound as electricity. It is a marvel to the scientist as well as to the novice. It is simple in its manifestations, but most complex in its organization and in its ramifications. It has been shown that light, heat, magnetism and electricity are the same, but that they differ merely in their modes of motion.

FIRST HISTORICAL ACCOUNT.--The first historical account of electricity dates back to 600 years B. C. Thales of Miletus was the first to describe the properties of amber, which, when rubbed, attracted and repelled light bodies. The ancients also described what was probably tourmaline, a mineral which has the same qualities. The torpedo, a fish which has the power of emitting electric impulses, was known in very early times.

From that period down to about the year 1600 no accounts of any historical value have been given. Dr. Gilbert, of England, made a number of researches at that time, principally with amber and other materials, and Boyle, in 1650, made numerous experiments with frictional electricity.

Sir Isaac Newton also took up the subject at about the same period. In 1705 Hawksbee made numerous experiments; also Gray, in 1720, and a Welshman, Dufay, at about the same time. The Germans, from 1740 to 1780, made many experiments. In 1740, at Leyden, was discovered the jar which bears that name. Before that time, all experiments began and ended with frictional electricity.

The first attempt to "bottle" electricity was attempted by Muschenbr[oe]ck, at Leyden, who conceived the idea that electricity in materials might be retained by surrounding them with bodies which did not conduct the current. He electrified some water in a jar, and communication having been established between the water and the prime conductor, his assistant, who was holding the bottle, on trying to disengage the communicating wire, received a sudden shock.