threads of cotton, and other light substances; the substances just mentioned as highly electric are, however, merely specimens. All objects, without exception, most probably are capable of being electrically excited; but some require more complicated contrivances to produce it than others.

Is there not a machine by which we are enabled to obtain large supplies of electric power at pleasure?

Yes; the electrical machine. It is made of different forms and sizes: for common purposes those of the simplest form are the best. A common form of the machine consists of a circular plate of glass, which can be turned about a horizontal axis by means of a suitable handle. This plate turns between two supports, and near its upper and lower edges are two pairs of cushions, usually made of leather, stuffed with horse-hair and coated with a mixture of zinc, tin, and mercury, called an amalgam. These cushions are the rubbers for producing friction, and are connected with the earth by means of a metal chain or rod. Two large hollow cylinders of brass with globular ends, each supported by two glass pillars, constitute the reservoir for receiving the electricity. They are called the prime conductors, and are supplied with U-shaped rods of metal, furnished with points along their sides, called combs, for the purpose of receiving the electricity from the glass plate, the arms of the U being held upon either side. The other ends of the conductors are connected by a rod from the middle of which projects another rod terminating in a knob, for delivering the spark.

On turning the plate, a faint snapping sound is heard, and when the room is darkened, a spark is seen to be thrown out from the knob projecting from the prime conductors.

Many curious and interesting experiments may be performed by means of the machine, illustrating the general properties of electricity. For instance: a person standing on an insulated bench, that is, a bench with glass legs, or having the legs resting on glass, and having one hand on the conductor, can send sparks, with the other hand, to everything and everybody about. This illustrates communication of electricity by contact. A wooden head, covered with long hairs, when placed on the conductor, illustrates electrical repulsion, by the hairs standing on end.

If the hand is held to the knob, sparks will pass from it in rapid succession, causing in the hand a sensation of pain. This is called an electric shock, and is caused by the electric fluid occasioning a sudden motion by the contraction of the muscles through which it passes. The force of the shock is in proportion to the power of the machine.

What are the Muscles?

Bundles of thin fleshy fibres, or threads, fastened to the bones of animals, the contraction and expansion of which move the bones or perform the organic functions of life.

What is Twilight?

The light from the first dawning of day to the rising of the sun; and again between its setting and the last remains of day. Without twilight, the sun's light would appear at its rising, and disappear at its setting, instantaneously; and we should experience a sudden transition from the brightest sunshine to the profoundest obscurity. The duration of twilight is different in different climates; and in the same places it varies at different periods of the year.

How is it produced?

By the sun's refraction—that is, the variation of the rays of light from their direct course, occasioned by the difference of density in the atmosphere.

What is the poetical name for the morning Twilight?

Aurora, the goddess of the morning, and harbinger of the rising sun: whom poets and artists represent as drawn by white horses in a rose-colored chariot, unfolding with her rosy fingers the portals of the East, pouring reviving dew upon the earth, and re-animating plants and flowers.

What remarkable phenomenon is afforded to the inhabitants of the polar regions?

The Aurora Borealis, or Northern Lights, a luminous appearance in the northern parts of the heavens, seen mostly during winter, or in frosty weather, and clear evenings; it assumes a variety of forms and hues, especially in the polar regions, where it appears in its perfection, and proves a great solace to the inhabitants amidst the gloom of their long winter's night, which lasts from one to six months, while the summer's day which succeeds it lasts in like manner for the same period of time.

Of what nature is the Aurora Borealis?

It is decidedly an electrical phenomenon which takes place in the higher regions of the atmosphere. It is somehow connected with the magnetic poles of the earth; and generally appears in form of a luminous arch, from east to west, but never from north to south.

In what country is it seen constantly from October to Christmas?

In Siberia, where it is remarkably bright. On the western coast of Hudson's Bay, the sun no sooner disappears, than the Aurora Borealis diffuses a thousand different lights and colors with such dazzling beauty, that even the full moon cannot eclipse it.

CHAPTER II.

Corn, Barley, Pearl Barley, Oats, Rye, Potatoes, Tea, Coffee, and Chocolate.

What is Corn?

Corn signifies a race of plants which produce grain in an ear or head, fit for bread, the food of man; or the grain or seed of the plant, separated from the ear.

What is generally meant by Corn?

In this country, maize, or Indian corn, is generally meant; but, in a more comprehensive sense, the term is applied to several other kinds of grain, such as wheat, rye, barley, oats, &c.

Where was Corn first used?

It is uncertain. The Athenians pretend that it was amongst them it was first used; the Cretans, Sicilians, and Egyptians also lay claim to the same. From the accounts in the Bible, we find that its culture engaged a large share of the attention of the ancient Hebrews.

Who were the Athenians?

Inhabitants of Athens, the capital city of Greece.

Who were the Cretans?

The inhabitants of Crete, an island of the Archipelago.

Who were the Sicilians?

Inhabitants of Sicily, the