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Interesting Particulars Concerning the Magnet

Fire-irons which have rested in an upright position in a room during the summer months are often highly magnetic.

Iron bars standing erect, such as the gratings of a prison cell, or the iron railings before houses, are often magnetic.

The great iron-clad ships, which have now replaced the wooden walls of Old England, are powerfully magnetic, and therefore affect the compass by which the vessel is steered; ingenious arrangements are therefore made to correct the effect of the local attraction, so that the man-of-war may be steered correctly. Magnetism may be made to pass through a deal board; to exhibit which lay a needle on the smooth part above, and run a magnet along the under side, and the needle will be found to follow the course of the magnet. A magnet dipped into boiling water loses part of its magnetism, which however returns upon its cooling.

A sudden blow given to a magnet often destroys its magnetic power. In the above picture we see portrayed the power of the magnet from a comic point of view. A gentleman in armour and his faithful squire have trespassed upon the domain of a magician where the rocks are of a magnetic quality. The steel armour is so firmly attracted to the cliff that its owner is secured in a very undignified position, his squire trying in vain to release him from his predicament. Even the sword and spear obey the same invisible force, and attach themselves to the same rock to which their unhappy master is fastened. Above we see the magician, the author of all the mischief, who seems to be enjoying the results of his handiwork. Here we have the idea of magnetism, as elaborated by the imagination of those who write fairy tales; but it must be confessed that the most ambitious of such writers would fail to imagine such wonders as the magnet works in reality. What writer, for instance, would have dared to prophecy such an apparent impossibility as the mariner's compass--which guides the sailors of all nations to their required havens? who would have imagined that a magnetised needle would be able by its deflections to convey thoughts from one end of the world to the other? Even Shakespeare, the greatest writer which the world ever produced, speaks by the mouth of one of his fairy creations of "putting a girdle round the earth in forty minutes." The power of magnetism in the electric telegraph actually accomplishes this wonderful feat, in far less time. But the wonders of magnetism do not stop here, and perhaps the most remarkable discoveries in connection with it have been made in the past few years. Of these may be particularly mentioned the electric light, which, obtained from the power of magnetism, has lately been so much applied to industrial purposes; the telephone, by which the sounds of articulate speech are instantaneously conveyed over immense distances; and, lastly, the microphone, which in connection with the telephone is likely to do so much in the future in the investigation of minute sounds. These three subjects are of so much importance that I shall devote some little space in considering each in detail, commencing with the production of light by means of electro-magnetic machines.

At the commencement of the present century, Sir Humphrey Davy first obtained the electric light. In the course of some experiments with a very powerful galvanic battery, he fastened some pieces of charcoal to the terminal wires. Upon bringing the charcoal points together, he found that a most brilliant light appeared between them. The heat evolved was so great that the most refractory substances, such as quartz, lime, magnesia, the diamond, melted like wax in the flame of an ordinary candle. But the most noticeable feature in the experiment was the intensity of the light, which seemed in its character to rival sunlight itself.