motion in this wonderful fluid, that the necessary balance is maintained.

Another ingredient in the atmosphere is moisture. This is very sensibly acted on by heat. It is the principle of heat which evaporates the moisture from the earth, and causes it to mix with the air, and to float in it, sometimes as an invisible fluid, sometimes in the form of clouds, and which at other times causes it to be precipitated in the form of rain. Now, the remarkable circumstance is, that although heat is the agent in these operations, the change of temperature does not so affect the process as to cause the operations to cease, or very materially to disturb them. Evaporation goes on both at a low and a high temperature, and in both states clouds are formed and rain falls. This is owing to a very peculiar provision, obviously imposed by consummate wisdom. The air is made capable of containing vapour in a certain proportion to its temperature; and it is not till it be saturated that the evaporation from the surface of water ceases, or that deposition takes place. The temperature of the air in winter does not, indeed, admit of the same quantity being held in solution as in summer; but up to a certain point it is equally capable of sustaining it in the one case as in the other. Evaporation, therefore, takes place in very cold weather, even from ice and snow; and the water thus infused into the air is carried up into the higher regions, till it reaches the point where the temperature is such as to correspond with the quantity of moisture. Precisely the same process takes place in summer, with this difference, that the evaporation is much more abundant, and the air, owing to its increased temperature, is capable of containing a far greater quantity in solution. Again, the point of deposition is regulated by a similar law, with a similar difference. Deposition does not take place either in winter or summer, till the air is more than saturated; but this effect is produced at very different temperatures, according to the quantity actually held in solution, so that a very slight degree of cold will form clouds

and cause rain in summer, compared with what is necessary to occasion the same phenomena in winter. Hence the processes of evaporation and deposition are made, by this very peculiar law, always to bear a relation to the actual temperature of the season; and such a balance is kept up between these processes, as is admirably suited to the wants of vegetable and animal life.

I may add to all this the properties of the atmosphere, by means of which it is made the vehicle of light and sound, and the means of respiration. The changes which the air undergoes by the operation of heat and cold, might easily be supposed, and might even perhaps, reasoning without the aid of experience, be expected to produce a material alteration on such properties. But although these changes are so considerable in different seasons, and in different climates, we do not find that the laws either of vision or of acoustics are in any material degree affected by them,—or that the action of the lungs, either in man or the lower animals, is impeded or deranged.

In attending to the complicated nature of the atmosphere, and the various important functions it has to perform, and in considering the diversified modifications it must necessarily undergo by the alteration of its temperature, both in the various latitudes of the globe, and in the different seasons of the year, it does seem impossible to doubt that the uniformity of its properties, and of its salutary influences under all these modifications, has been provided for, by what Whewell, considering that subject in a more extended view, justly calls "a most refined, far-seeing, and far-ruling contrivance." So many opposing forces, and the mingling of such subtle and fearfully active elements, appear in the most quiescent state to require amazing prospective skill for their regulation and control; and when we find them, even under the influence of extensive changes, still harmoniously combining their powers for the general good, we cannot but perceive that all this could not be effected

but by the same paternal Hand which originally called their powers into action.-Sacred Philosophy of the Seasons.

THE DIVING BELL AT THE POLYTECHNIC

INSTITUTION, REGENT-STREET,

Is constructed of cast-iron, and weighs three tons; is about one-third open at the bottom, and has a seat around for the divers: it is lit by twelve openings, of thick plate-glass, secured by brass frames screwed to the bell; six of these lights being triangular, and in the crown, and six square, in the side. The bell is “ suspended by a massive chain to a large swing crane, with a powerful crab, the windlass of which is grooved spirally ; the chain passes over four times into a well beneath, and to it are suspended the compensation weights," which, by acting upon the spiral shaft, accurately counterpoise the bell at all depths. It is supplied, by two powerful pumps of eight-inch cylinder, with air, conveyed by a leather hose to any depth.

The bell is constructed with all the improvements which modern science has suggested; the engineers being Messrs. Cottam and Hallan. It is slightly conical; five feet in height, and four feet eight inches in diameter at the mouth its thickness is one and a half inch at the top, and two and a half inches at the bottom: the seat (which extends nearly round the inside) and the flooring, or support for the feet, are of wrought-iron grating; both being covered with wood, and the seat carpeted, to suit amateur divers, of whom there is a fair proportion. Within the bell is affixed a knocker, (such as we commonly see on street-doors,) under which is painted :—

"More Air-Knock Once.
Less Air-Knock Twice.

Pull up-Knock Three Times."

There is likewise affixed a written caution,-"Visiters are requested to keep their seats, and their feet on the board." Instead of the strong lenses, or "bull's-eye lights," common in old bells, the windows are filled with plate-glass

seven-sixteenths of an inch thick. The leather hose is lined with caoutchouc cloth, and fitted inside with spiral wire. A peculiar provision is made for adding weights to the bell, and securing them with flanges to the outer rim; and six massive. vertical straps meet on the crown in a double ring, by which the bell is suspended from the

crane.

The bell is put into action several times daily: it will contain four or five persons seated; each pays one shilling for a descent ;* and so universal is the public curiosity, that ladies and children are frequently occupiers of the seats.-Year-Book of Facts.

MINISTRY OF ANGELS.

WHAT need have we to dispute whether every particular saint has a guardian angel, when we are sure he has a guard of angels about him ?-M. HENRY.

Angels have two offices,-to sing above, and watch below.-LUTHER.

When Deity is in the house, the angels are at the door.-STRATTON.

Ministerial success increases the joy of angels. We believe that they attend on our footsteps, that they watch for our success, that they may carry back the news of repentant sinners, and that they may strike their harps to new songs of joy. Were the invocation lawful, we would say, "STAY, SPIRITS, STAY!" But we would rather call upon the God of angels, and pray that heaven may rejoice to witness the conversion of your souls.-J. PARSONS.

If our world be the cradle of the universe, the place where myriads of immortal beings are nursed, trained up to people heaven, and inherit eternal glory, we shall not wonder at the subjection of the higher parts of creation to this, nor if on earth angels should for a time become nursing fathers.-BLUNDEL.

* "We understand the diving bell is a complete lion, and turns in nearly 1,000l. per annum."-Railway Magazine, October, 1838.

God's people, at death, are returning to Canaan, to their Father's house; and then the angels of God will meet them to congratulate them on the happy finishing of their servitude, and to carry them to their rest.— M. HENRY.

"The chariots of fire and the horses of fire" receive the disembodied spirit, and the once-dejected penitent is conveyed to his inheritance,

"In the blest kingdoms meek of joy and love,
There entertain him all the saints above

In solemn troops and sweet societies,
Who sing, and singing in their glory move,
And wipe the tears for ever from his eyes."

-DR. STYLES.

HINTS FOR STUDENTS.

A LATE morning student is a lazy one, and will rarely make a true scholar; and he who sits up late at night, not only burns his life's candle at both ends, but puts a redhot poker to the middle.-DR. A. CLARKE.

If I omit reading a portion of the Scriptures in the morning, nothing goes well with me through the day.—SIR MATTHEW HALE.

When I meet with a passage in the Bible, the hidden meaning of which I cannot penetrate, I tie a knot and go on.-DR. STONEHOUSE.

Learning, without religion, is but as a sounding brass, and a tinkling cymbal—a compass without its polarity-a watch without its regulator--a steam-engine without its safety-valve.-SIR JAMES GRAHAM.

One day filled up according to a previous plan, is worth more than a week, filled up without any plan.

THE BENEFIT OF PRAYER.

PRAYER is the bellows that blows up the affections; and a Christian is most active when his affections are most lively. Prayer is to the soul as the animal spirits are to the