There are many species of Polistes, mostly belonging to Australasia and tropical America, the latter displaying the greatest variety of form and structure in the nest.
USEFUL ARTS.
CHAPTER XV.
Electricity, Magnetism, and Galvanism mutually convertible.—The Force co-extensive with Nature.—Uses of Thunder-storms.—Languor from Want of Electricity.—Frictional and Voltaic Electricity.—Origin of the Name.—Structure of the Voltaic Pile.—A simple Example of the Pile.—Nerves of a Frog’s Leg.—The Electric Shock, and how to produce it.—The Electric Jar and Battery.—Animal Electricity.—The Torpedo and Electric Eel.—Structure of the Electric Apparatus.—The Electric Spark obtained from both Fishes.—Channels of Electricity in the Body.—The Will and the Muscles.—Electricity the conducting Agent.—The Human Body permeated by Nerves.—Telegraph Wires and the Nervous System.—Lightning and the Electric Spark.—The Electric Light and its Power.—The Fire-fly, the Glow-worm, and the luminous Inhabitants of the Sea.—Magnetism and Diamagnetism.—The Electric Telegraph and the Compass.—The Principle identical in both Instruments.
Electricity and Magnetism.
IT has long been known that Electricity, Galvanism, and Magnetism are but different manifestations of the same force, and that one can be converted into the other at will. It is also known that this wonderful and most important principle lies latent in everything, and only needs the proper machinery to evoke it.
The few following illustrations are intended to show its prevalence in Nature, and that human art does not create, but only makes manifest a power that exists, but lies latent until called forth.
Without going into details, which would occupy the whole of such a volume as this, I may mention that Electricity saturates all the material creation, and that even man himself is not only a reservoir of electricity, but that he feels positively ill if the normal amount be not supplied.
Take, for example, the hours that precede a thunder-storm. We feel languid and depressed. We cannot bring our thoughts together. We are almost incapable even of bodily labour. The reason is, that the portion of the earth on which we live has parted with some of its electricity, and has drawn it out of our bodies.
Then comes the welcome thunder-storm; clouds overcharged with electricity come to restore the balance. The lightning flashes from the clouds to the earth as soon as they are near enough; the rain falls, carrying with it stores of silent electricity; and in an hour or two all seems changed.
The air, which hitherto seemed to afford no nourishment to the lungs, is bracing and invigorating. The nervous system recovers its tension, and the brain can act without a painful effect. All Nature seems to put on a different aspect, and brightness and vigour take the place of dulness and languor.