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The Boy Electrician
This file was produced from page images at Google Books.
Transcriber's Note
This book was transcribed from scans of the original found at Google Books. I have rotated some images. The more complex tables are treated as images.
The
Boy
Electrician
ALFRED P MORGAN
BOSTON
LOTHROP, LEE & SHEPARD CO.
Entered at Stationers' Hall, London
Published July, 1914
THE BOY ELECTRICIAN
NORWOOD PRESS
Berwick & Smith Co.
Norwood, Mass. U.S.A.
TO THE SELF-RELIANT
OUR FUTURE ENGINEERS AND SCIENTISTS, THAN WHOM
NONE IN THE WHOLE WORLD ARE BETTER ABLE
TO WORK OUT AND SOLVE THE PROBLEMS
THAT EVER CONFRONT YOUNG
MANHOOD, THIS BOOK
IS CORDIALLY
DEDICATED.
THE BOY ELECTRICIAN
INTRODUCTION
Once upon a time, and this is a true tale, a boy had a whole railroad system for a toy. The train ran automatically, propelled by tiny electric motors, the signals went up and down, the station was reached, a bell rang, the train moved on again and was off on its journey around many feet of track to come back over the old route.
The boy viewed his gift with raptured eyes, and then his face changed and he cried out in the bitterness of his disappointment: "But what do I do?" The toy was so elaborate that the boy was left entirely out of the play. Of course he did not like it. His cry tells a long story.
The wireless outfit is not a symbol, but something that you can both hear and see in operation even though you may not understand the whispering of the dots and dashes. And as soon as the mystery of this modern wonder more firmly grips your imagination, you perhaps may come to realize that we are living more and more in the age of electricity and mechanism. Electricity propels our trains, lights our houses and streets, makes our clothes, cures our ills, warms us, cooks for us and performs an innumerable number of other tasks at the turning of a little switch. A mere list is impossible.
To the boy interested in science, a wide field is open. There is no better education for any boy than to begin at the bottom of the ladder and climb the rungs of scientific knowledge, step by step. It equips him with information which may prove of inestimable worth in an opportune moment.
ALFRED P. MORGAN
UPPER MONTCLAIR, N. J.
Over two thousand years ago, in far-away Asia Minor, a shepherd guarding his flocks on the slope of Mount Ida suddenly found the iron-shod end of his staff adhering to a stone. Upon looking further around about him he found many other pieces of this peculiar hard black mineral, the smaller bits of which tended to cling to the nails and studs in the soles of his sandals.
This mineral, which was an ore of iron, consisting of iron and oxygen, was found in a district known as Magnesia, and in this way soon became widely known as the "Magnesstone," or magnet.
This is the story of the discovery of the magnet. It exists in legends in various forms. As more masses of this magnetic ore were discovered in various parts of the world, the stories of its attractive power became greatly exaggerated, especially during the Middle Ages. In fact, magnetic mountains which would pull the iron nails out of ships, or, later, move the compass needle far astray, did not lose their place among the terrors of the sea until nearly the eighteenth century.
For many hundreds of years the magnet-stone was of little use to mankind save as a curiosity which possessed the power of attracting small pieces of iron and steel and other magnets like itself. Then some one, no one knows who, discovered that if a magnet-stone were hung by a thread in a suitable manner it would always tend to point North and South; and so the "Magnes-stone" became also called the "lodestone," or "leading-stone."
These simple bits of lodestone suspended by a thread were the forerunners of the modern compass and were of great value to the ancient navigators, for they enabled them to steer ships in cloudy weather when the sun was obscured and on nights when the pole-star could not be seen.
Experiments with Magnetism
The phenomena of magnetism and its laws form a very important branch of the study of electricity, for they play an important part in the construction of almost all electrical apparatus.
Dynamos, motors, telegraphs, telephones, wireless apparatus, voltmeters, ammeters, and so on through a practically endless list, depend upon magnetism for their operation.
Small horseshoe and bar magnets can be purchased at toy-stores. They can be used to perform very interesting and instructive experiments.
Stroke a large darning-needle from end to end, always in the same direction, with one end of a bar magnet. Then dip the needle in some iron filings and it will be found that the filings will cling to the needle. The needle has become a magnet.
Dip the bar magnet in some iron filings and it will be noticed that the filings cling to the magnet in irregular tufts near the ends, with few if any near the middle.
There exists between magnets and bits of iron and steel a peculiar unseen force which can exert itself across space.
The power with which a magnet attracts or repels another magnet or attracts bits of iron and steel is called
Place some small carpet-tacks on a piece of paper and hold a magnet above them. Gradually lower the magnet until the tacks jump up to meet it.
Then try some nails in place of the tacks. The nails are heavier than the tacks, and it will require a greater force to lift them. The magnet will have to be brought much closer to the nails than to the tacks before they are lifted, showing that the force exerted by the magnet is strongest nearest to it.
Magnetize a needle and lay it on a piece of cork floating in a glass vessel of water. It will then be seen that the needle always comes to rest lying nearly in a north and south line, with the same end always toward the north.
The name is usually abbreviated to simply the north and south poles. The north pole of a magnet is often indicated by a straight line or a letter N stamped into the metal.
A magnetized needle floating on a cork in a basin of water is a simple form of
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