and that the hill was raised while a posset of milk was seething." Its name, however, seems to have signified the great hill. The diameter of Silbury Hill at top is 105 feet, at bottom it is somewhat more than 500 feet; it stands upon as much ground as Stonehenge, and is carried up to the perpendicular height of 170 feet, its solid contents amounting to 13,558,809 cubic feet. It covers a surface equal to five acres and thirty-four perches. It is impossible, at this remote period, to ascertain by whom, or for what precise purpose, this enormous mound of earth was raised; but from its proximity to the celebrated Druidical temple at Abury, it is supposed to have had some reference to the idolatrous worship of the Druids, and, perhaps, to contain the bones of some celebrated character.

According to Sir Richard Colt Hoare, who has investigated this subject with great skill and care, we may divide tombs of this description into, first, the long barrow, which is the largest of all, and generally of a long oval form; the circular barrow, shaped like an inverted bell, a bowl, &c. ; and the Druid barrow, which is large and circular, seldom of any great elevation, and surrounded by a ditch and embankment. Within the area of this embankment are generally found small conical heaps of earth, which in some instances have contained small articles, such as cups, lance heads, amber, jet, and glass beads. Although these have had the name of Druid barrows imposed on them, Sir Richard Hoare is inclined to believe that they were not formed by the Druids, but that they were intended as burial places for the female portion of the British tribes.

Sometimes two of these barrows were enclosed in one circle; they are then supposed to have been the tombs of two friends or near relations.

The manner in which the ancient Britons buried their dead varied at different periods. The author we have already noticed says, "I am of opinion that the method of burying the body entire, with the legs gathered up, was the most ancient; that the custom of burning the dead succeeded, and continued along with the former; and that the mode of burying the body entire, and extended at full length, was of the latest adoption."

The most primitive method of disposing of the ashes of the dead was by depositing them on the floor of the barrow, or in a little hollow cut in the native chalk. The funeral urn, in which the ashes of the dead were secured, was the refinement of a later age. The bones, when burnt, were collected, and placed within the urn, which was deposited, in almost all cases, with its mouth downwards, in a hollow cut in the chalk; of these urns, which are far from uncommon, the larger are found to contain the burnt bones of the deceased, and the smaller are supposed to have held some description of food.

Exercise in Spelling-XIV.

Collect the principal words in each paragraph of the preceding lesson. Divide each word, mark its proper accentuation, and give its meaning according to the context.

Arithmetic-XII. Proportion.

1. If 30 pecks of wheat serve 18 persons for 11 days, how long will 144 pecks serve 12 persons?

2. If 10 horses can be kept 30 days for £18, how many can be kept for 10 days for £27?

3. If 8 men dig a trench 20 yards long in 12 days by working 10 hours per day, how many will dig a trench 16 yards long in 4 days, working 8 hours per day?

A SOLILOQUY ON SLEEP.

From Shakespeare's Historical Play of "King Henry IV." The first part to be read in slow time, with emphatic pauses; the latter part quicker and with animation.

How many thousands of my poorest subjects
Are at this hour asleep! O gentle sleep!
Nature's soft nurse, how have I frighted thee,
That thou no more wilt weigh my eye-lids down,
And steep my senses in forgetfulness?

Why rather, Sleep, liest thou in smoky cribs,
Upon uneasy pallets stretching thee,

And hushed with buzzing night-flies to thy slumber,
Than in the perfumed chambers of the great,
Under the canopies of costly state,

And lulled with sounds of sweetest melody?
O thou dull god, why liest thou with the vile,
In loathsome beds, and leavest the kingly couch
A watch-case to a common 'larum bell?
Wilt thou upon the high and giddy mast,
Seal up the ship-boy's eyes, and rock his brains
In cradle of the rude imperious surge;
And in the visitation of the winds,

Who take the ruffian billows by the top,
Curling their monstrous heads, and hanging them
With deafening clamours in the slippery shrouds,
That, with the hurry, death itself awakes?
Canst thou, oh partial Sleep, give thy repose
To the wet sea-boy in an hour so rude;
And in the calmest and the stillest night,
With all appliances and means to boot,
Deny it to a king? Then, happy lowly clown!
Uneasy lies the head that wears a crown!

THE AIR WE BREATHE.

PART I.

The Almighty Creator having destined this globe for the residence of man, proceeded to surround it with an atmosphere, or mass of aerial fluid, essential to his comfort and existence. Though invisible, it is in constant action, affecting the properties of nearly all bodies with which it comes into contact; and it produces the most important effects where neither its presence nor its agency is suspected by those who are ignorant of philosophy.

The air we breathe was long supposed to be a simple, elementary body, one of the four into which the ancients resolved the material universe-the others being fire, earth, and water. But here, as in other cases, their opinion has been proved erroneous; for it is now well known that atmospheric air is composed of three gases-azotic, or

nitrogen, oxygen, and carbonic acid gas-which differ essentially in property from each other, and from the whole. The proportions are, 78 parts of nitrogen, nearly 22 of oxygen, and about one quarter of a part of carbonic acid gas, in 100 parts, by bulk, of atmospheric air. Besides these gaseous fluids, the atmosphere contains particles of various substances in a state of mixture or solution. Aqueous vapour, the electric fluid, numerous exhalations from the earth's surface, and from all bodies upon or near it, are mingled with the air itself in apparent confusion, and yet so as not to interfere with its perpetual use, and not often, or to any great extent, with its salutary nature. The atmosphere thus surrounding the earth, and sustaining the life of its inhabitants, forcibly reminds us of the protection and support of our Heavenly Father," in whom we live, and move, and have our being."

Though invisible to human sight, the atmosphere is cognizable by some of our other senses; and its effects, as determined by observation and experiment, point out to us the following as its principal qualities.

;

Its aërial part, like other gaseous substances, is highly elastic; by which it is capable of being compressed into a smaller space, and of recovering its former state when the force is removed. If an open vessel full of air be inverted and immersed in water, the resistance it offers to farther immersion is a proof of the elasticity of the air it contains and if a blown bladder be pressed between the hands, the included air offers a sensible resistance, and when the pressure is removed its former figure is immediately recovered. The elastic force is always proportional to the density of the air; and it is difficult, if not impossible, to destroy it. Desaguliers found that air, after being confined for half a year in a wind-gun, still retained its original powers; and Roberval, after keeping it in a state of condensation for a much longer period, found that it possessed the same elastic power as at first. In some cases, however, of very strong pressure, it has been found to be diminished; and it appears that moist air is the most elastic. The elasticity of the air exerts itself equally in all ways; and when it is at liberty from the cause

which compresses it, it expands equally in every direction, in consequence of which it always assumes a spherical figure in the interstices of the fluid in which it is lodged. The expansion of air, when only its compressing force is taken off, is surprisingly great: it has been known, in certain experiments, to expand itself into 13,679 times its original space by its own natural power, without the application of fire.

The elasticity of air, under the same pressure, is increased by heat and diminished by cold, at the rate of about 1-435th part for every degree of heat, by Fahrenheit's thermometer.

The atmosphere-the name of which is derived from two Greek words, which signify a sphere and vapoursurrounds the earth equally, it is probable, on every side, to a height which cannot be exactly ascertained, but which is generally supposed to be between forty and sixty miles. Its existence at the height of forty-five miles has been pretty well determined, from its power of refracting the sun's rays at an angle denoting that elevation, and which is the cause of twilight.

The weight and pressure of the atmosphere now demands consideration. The air, though invisible, and yielding to the slightest pressure, is not destitute of weight. Torricelli found that a column of air the height of the atmosphere is sufficient to counterbalance a column of water of equal base in the tube of a common pump, about 34 feet in height, and a similar column of mercury from 29 to 30 inches high. This is confirmed by common experience. The specific gravity of atmospheric air, in comparison with water, is as 1 to 1,000; that is, a cubic foot of air weighs, at a mean, 1, while a cubic foot of water weighs 1,000 ounces avoirdupois, and a cubic foot of mercury 13,600 ounces. The pressure of the atmosphere on every square inch of surface is about 15 pounds; and if we suppose the surface of a man's body about 15 square feet, he must sustain 32,400 pounds, or nearly 14 tons' weight, for his ordinary load. If this were laid upon his shoulders, it would crush him to the earth; but it is not only distributed over the whole of his body, acting upwards as well as