facility, while others conduct it with difficulty, and others not at all. Substances of the first kind are called 2 conductors, and those of the last 3 non-conductors.

A body is said to be 1 insulated when it is supported by an electric. Thus a stool standing on glass legs is insulated, and a plate of metal laid on a plate of glass is insulated.

When large quantities of the electric fluid are wanted for an experiment, or for other purposes, it is procured by an electrical machine. These machines are of various forms, but all consist of an electric substance of considerable dimensions; the rubber by which this is excited; the prime conductor, on which the electric matter is accumulated; the insulator, which prevents the fluid from escaping; and machinery, by which the electric is set in motion.

It was proved by Dr. Franklin that the electric fluid and lightning are the same substance, and this 'identity has been confirmed by subsequent writers on the subject.

If the properties and phenomena of lightning be compared with those of electricity, it will be found that they differ only in respect to degree. Thus lightning passes in irregular lines through the air; the discharge of an electrical battery has the same appearance. Lightning strikes the highest pointed objects, takes in its course the best conductors, sets fire to non-conductors, or rends them to pieces, and destroys animal life; all of which phenomena are caused by the electric fluid.

Buildings may be secured from the effects of lightning, by fixing to them a metallic rod, which is elevated above every part of the edifice, and continued to the ground, or to the nearest water.

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4. Iron steam boats are therefore considered safe, for although being conductors they attract the lightning, yet having direct communication with the sea, which is also a conductor, the electric fluid passes harmlessly downward; its tendency being always to the earth.

ITALY.

Roman History (concluded).

THE 'pope still governs Rome, and other adjacent territories in the centre of Italy. His dominions are bounded north by Lombardy, and in other directions by the Mediterranean Sea and the Adriatic, and by the kingdom of Naples, Modena, and Tuscany. He is the head of the Roman Catholic church throughout the world.

The city of Rome at present is thirteen miles in 'circumference. The greater part of it has a dark, gloomy, and desolate appearance; it is full of old ruins of palaces and temples, and other magnificent edifices of the ancient Romans. Innumerable statues are supposed to be buried under ground.

There are also many works still existing, written by old Roman authors. These are in the Latin language. Many of them are interesting, From some of them modern nations have derived their most valuable laws and institutions.

Italy is now divided into several distinct kingdoms, or states. Each of these has its history.

The kingdom of Naples, or the kingdom of the Two Sicilies, includes the island of Sicily and the southern extremity of the peninsula of Italy.

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The history of Naples, after it was separated from the Roman empire, possesses very little interest. It passed first into the hands of one tribe of northern invaders, and then into the hands of another. After this it was subject to Spain and other countries, until at length it became

1. Vide Root. 2. The pope became a temporal prince by the acquisition of the Exarchate of Ravenna in the eighth century; but Matilda, Countess of Tuscany, gave the principal possessions by will to Pope Gregory 7th, at the latter end of the eleventh century. 3. Naples was conquered by the Saracens in 1012. The French obtained it in 1265. Spain conquered it in 1504; the Austrians in 1706. 4. Venice gained her riches by the trade of the Mediterranean Sea, and was ruined by the discovery of the passage to India by the Cape of Good Hope.

an independent country, under the government of its present race of kings.

The history of Venice is more interesting.

When the

northern barbarians invaded Italy in 452, the inhabitants living in the vicinity of the present city of Venice settled in the marshes along the border of the sea, and supported themselves by fishing, making salt, and by commerce.

In the year 809, they commenced building the city of Venice on a little island called Rialto. To this place they transported their riches, and soon the new city became the capital of the republic of Venice. The city and state increased, until at length Venice was one of the most powerful states in the world.

The inhabitants paid great attention to commerce, and such was the number of their ships, that in the eleventh century, Venice sent a fleet of two hundred sail to assist in the first crusade.

The power of Venice continued to increase, and in process of time, the proud city of Constantinople was captured by its armies, aided by the crusaders. The spoils of the captured city, consisting of gems and jewellery, books, marbles, pictures, statues, obelisks, and other costly treasures, were chiefly carried to Venice.

The republic 'prospered for many years. But toward the close of the last century, it fell a victim to the power of France, and since the year 1798, it has been attached to the empire of Austria.

GEOGRAPHICAL.-Write the names of the cities in the kingdom of Naples, which includes all the southern part of Italy and the island of Sicily.

What are the latitude and longitude of Turin, Trieste, Venice, Florence, Rome, Naples, and Mount Etna ?

CHRONOLOGICAL.-Italy, next to Greece, is most celebrated for its orators, poets, historians, painters, sculptors, architects, and musicians; the principal were Cicero, orator, d. 43 B.c. Virgil, poet, b. 70 в.c. Livy, historian, 240 B.C. Tacitus, historian, d. A. D. 276. Lucretius, poet and philosopher, d. 54 B. C. Dante, poet, b. 1265 A. D. Tasso, poet, b. 1544. Ariosto, poet, b. A. D. 1474. Galileo, philosopher, b. 1564. Raphael, painter, b. A. D. 1483. Titian, painter, b. 1480. Romano, painter, b. 1492. Correggio, painter, b. 1490. Paul Veronese, painter b. 1530. Michael Angelo, painter, and architect of St. Peter's at Rome, b. 1474.

ELECTRICITY.
Galvanism.

GALVANISM is similar in its effects to electricity; hence it is considered as a branch of the science. It owes its 'origin to Galvani, a professor of Bologna in Italy.

It has been found that when two pieces of metal act upon each other, an oxydation or rusting takes place. If a piece of zinc and a piece of copper be laid on each other in a cup of water, oxydation rapidly ensues. If instead of employing one piece of zinc and one piece of copper, a great number were to be employed, an effect proportionably great would be produced. This galvanic action is occasioned by the chemical action of bodies upon each other.

The instrument which affords a perpetual current of galvanic fluid is called a galvanic battery. It consists of a trough of baked wood about three inches deep and as many broad. In the sides of the vessel are grooves opposite to each other, and about a quarter of an inch apart. Into each pair of these opposite grooves is put a plate of zinc and silver, or zinc and copper, soldered together.

These plates are fixed in the grooves in the proper order of silver and zinc, silver and zinc, by a cement made of five parts of resin, four of bees' wax, and two parts of powdered ochre. This cement must be run in very carefully, so as absolutely to prevent any communication between the different cells, which would entirely prevent the action of the machine. The cells are then filled with water, containing a little acid, common salt, or muriate of ammonia.

When a communication is made between the first and last cell, by means of the hands, a violent shock is felt, because the person stands in a position for the galvanic current to pass through him, forming a rent in the galvanic circle.

If the young student be desirous of having still more sensible proof of the effects of galvanism, let him hold a wire to the top of the battery, and let him place one end of a silver spoon to the lower part, and the other end within his mouth, so as to touch the gums,-a severe set of shocks will be felt. In performing this experiment, move the spoon to the roof of the mouth, and a strong sensation will be felt.

Galvanism, like electricity, may be communicated to many persons at the same time. Let half-a-dozen persons wet their hands: let the person at one end touch the lower end of the battery with a silver spoon, and let the person at the other end touch the top of the battery with a wire; a strong sensation will be experienced by them all, along the arm, at the joints, and under the arm-pits.

If a frog, scon after it has been killed, be stripped of its skin, and wires connected with the two ends of the galvanic battery be made to touch the muscles and nerves, the animal will exert its limbs, and leap as if alive. By the same means, a rabbit may be made to exert a force, sufficient to overcome the strength of a man who would try to prevent the motion of its limbs. After the animal becomes quite cold and stiff, galvanism has no effect upon it. These experiments, however, can only be successfully performed by experienced persons. To kill any living thing for the gratification of curiosity, is at best wanton cruelty.

Various attempts have been made to account for the phenomena of galvanism by the application of the laws which are known to govern electricity; but these have been attended with very little success; and the theory of this science is involved in considerable uncertainty. All that can be said to be fully established is, that the primary agent in the evolution of electricity is the force of chemical attraction.

1. Vide Root.

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