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83 pages

English

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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.

Sujets

Electronique & télécommunications

Engineering

Technology

Sciences et techniques

Electrical

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Publié par	eBookIt.com
Date de parution	03 août 2013
Nombre de lectures	2
EAN13	9781456619503
Langue	English

Informations légales : prix de location à la page 0,0150€. Cette information est donnée uniquement à titre indicatif conformément à la législation en vigueur.

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WARNING: This book of one hundred years ago describes experiments which are too dangerous to attempt by either adults or children. It is published for historical interest only.
Fig. 1. WORK BENCH
TABLE OF CONTENTS
COVER IMAGE
TITLE PAGE
INTRODUCTORY
CHAPTER I: THE STUDY OF ELECTRICITY. HISTORICAL
CHAPTER II: WHAT TOOLS AND APPARATUS ARE NEEDED
CHAPTER III: MAGNETS, COILS, ARMATURES, ETC.
CHAPTER IV: FRICTIONAL, VOLTAIC OR GALVANIC, AND ELECTRO-MAGNETIC ELECTRICITY
CHAPTER V: HOW TO DETECT AND MEASURE ELECTRICITY
CHAPTER VI: VOLTS, AMPERES, OHMS AND WATTS
CHAPTER VII: PUSH BUTTONS, SWITCHES, ANNUNCIATORS, BELLS AND LIKE APPARATUS
CHAPTER VIII: ACCUMULATORS. STORAGE OR SECONDARY BATTERIES
CHAPTER IX: THE TELEGRAPH
CHAPTER X: HIGH TENSION APPARATUS, CONDENSERS, ETC.
CHAPTER XI: WIRELESS TELEGRAPHY
CHAPTER XII: THE TELEPHONE
CHAPTER XIII: ELECTROLYSIS, WATER PURIFICATION, ELECTROPLATING
CHAPTER XIV: ELECTRIC HEATING, THERMO ELECTRICITY
CHAPTER XV: ALTERNATING CURRENTS, CHOKING COILS, TRANSFORMERS, CONVERTERS AND RECTIFIERS
CHAPTER XVI: ELECTRIC LIGHTING
CHAPTER XVII: POWER, AND VARIOUS OTHER ELECTRICAL MANIFESTATIONS
CHAPTER XVIII: X-RAY, RADIUM, AND THE LIKE
GLOSSARY OF WORDS USED IN TEXT OF THIS VOLUME
INTRODUCTORY
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.
CHAPTER I: 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 Muschenbrœck, 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.
In 1747 Sir William Watson fired gunpowder by an electric spark, and, later on, a party from the Royal Society, in conjunction with Watson, conducted a series of experiments to determine the velocity of the electric fluid, as it was then termed.
Benjamin Franklin, in 1750, showed that lightning was electricity, and later on made his interesting experiments with the kite and the key.
Discovering Galvanic Electricity.—The great discovery of Galvani, in 1790, led to the recognition of a new element in electricity, called galvanic or voltaic (named after the experimenter, Volta), and now known to be identical with frictional electricity. In 1805 Poisson was the first to analyze electricity; and when Å'rsted of Copenhagen, in 1820, discovered the magnetic action of electricity, it offered a great stimulus to the science, and paved the way for investigation in a new direction. Ampere was the first to develop the idea that a motor or a dynamo could be made operative by means of the electro-magnetic current; and Faraday, about 1830, discovered electro-magnetic rotation.
Electro-magnetic Force.—From this time on the knowledge of electricity grew with amazing rapidity. Ohm's definition of electro-motive force, current strength and resistance eventuated into Ohm's law. Thomson greatly simplified the galvanometer, and Wheatstone invented the rheostat, a means of measuring resistance, about 1850. Then primary batteries were brought forward by Daniels, Grove, Bunsen and Thomson, and electrolysis by Faraday. Then came the instruments of precision—the electrometer, the resistance bridge, the ammeter, the voltmeter—all of the utmost value in the science.
Measuring Instruments.—The perfection of measuring instruments did more to advance electricity than almost any other field of endeavor; so that after 1875 the inventors took up the subject, and by their energy developed and put into practical operation a most wonderful array of mechanism, which has become valuable in the service of man in almost every field of human activity.
Rapidity of Modern Progress.—This brief history is given merely to show what wonders have been accomplished in a few years. The art is really less than fifty years old, and yet so rapidly has it gone forward that it is not at all surprising to hear the remark, that the end of the wonders has been reached. Less than twenty-five years ago a high official of the United States Patent Office stated that it was probable the end of electrical research had been reached. The most wonderful developments have been made since that time; and now, as in the past, one discovery is but the prelude to another still more remarkable. We are beginning to learn that we are only on the threshold of that storehouse in which nature has locked her secrets, and that there is no limit to human ingenuity.
How to Acquire the Vast Knowledge.—As the boy, with his limited vision, surveys this vast accumulation of tools, instruments and machinery, and sees what has been and is now being accomplished, it is not to be wondered at that he should enter the field with timidity. In his mind the great question is, how to acquire the knowledge. There is so much to learn. How can it be accomplished?
The answer to this is, that the student of to-day has the advantage of the knowledge of all who have gone before; and now the pertinent thing is to acquire that knowledge.
The Means Employed.—This brings us definitely down to an examination of the means that we shall employ to instil this knowledge, so that it may become a permanent asset to the student's store of information.
The most significant thing in the history of electrical development is the knowledge that of all the great scientists not one of them ever added any