GROUP 14
POWER
CHAPTER S
The Story of Where Power Comes From, What It Does, & How It Works
An electric magnet used for unloading scrap-metal
THE OCEAN OF POWER WE LIVE IN ship in the wprld owes its safety and its guidance to the compass. Every boy and girl knows that a compass needle points to the North. Whichever way you turn, the little compass held in the palm of your hand will show you. where to look for the North. I t does so for two reasons. The compass needle is a magnet, and the Earth is.a huge magnet; and magnets affect each other by means of some invisible power which can pass through a stone wall, a glass window, a plate of wax, or any of the simple materials that woUld entirely shut out electricity. It is very important to try and imagine magnetism as a force spread out in space, and existing throughout space, no matter what it may be otherwise filled with. The mysterious force of magnetism was discovered over 2000 years ago by the shepherds of Asia Minor. As we have already seen, on the slopes of the mountains there is found an abundance of hard, black mineral, and the shepherds noticed that bits of this rocky substance would cling to the iron-shod ends of their crooks. This mineral was an ore of iron, and was found in the district of Magnesia, from '; which the power of magnetism took its :j name. The ore became known as the EVERY
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t'ELECTRICITY ;,
WIRELESS - OIL
magnes-stone; then, when it was found that a piece of the stone, if hung on a thread, would always point in one direction, it came to be called the leading-stone, or the lodestone. There were wonderful legends about the mysterious lodestone in the Middle Ages. Magnetic mountains were supposed to exist which would draw the iron nails out of ships if they approached too closely. Even after the first primitive compasses were made with bits of the lodestone itself sailors would fear that evil mountains of magnetic power would lead the compass astray and bring them to destruction. The compass first appeared in Europe sometime during the twelfth century. A tiny bar of iron was touched with a piece of lodestone, whereupon it acquired the powers of a magnet, and it was then mounted on a little piece of wood or cork which floated in a dish of water; later on it was rudely pivoted, but in neither case was there anything 'to show the points of the compass; it was merely known that the" needle" pointed North and South. Now if a m~gnet, when free to turn, will always point to the two poles of the Earth, we can easily understand that there must be some special power possessed by the poles, and it is not surprising to learn that
GAS . MOTORS . ENGINES . SHIPS 359