POWERS OF THE LORD.

O all ye Powers of the Lord, bless ye the Lord: praise Him, and magnify Him for ever.

HITHER can we go from Thy presence," or where can we cast our eyes without perceiving that we are surrounded by the Powers of the Lord? Above, below, around—in the air, in the water, on the earth and under the earth they reign supreme, revealing themselves at every turn in the mighty language of physical, chymical and vital force, bringing home to our minds at every instant our dependence upon Him, and filling us with thoughts of thankful adoration.

The Powers of the Lord shine forth in the Heavensin sun, moon and stars-with a grandeur which we cannot fully comprehend, but which nevertheless elevates our nature in the mere effort to grasp it. The sun proclaims itself the pivot of the solar system, sustaining and preserving by the power of gravity the planets that circle round it. On earth the operation of the same power of the Lord is no less necessary and universal. By solar gravity all things are attracted towards the centre of the sun, while by terrestrial gravity everything belonging to our globe is drawn towards the centre of

the earth.

Terrestrial gravity, therefore, counteracts the centrifugal tendency of objects resulting from the earth's rotation, and keeps them fixed upon its surface with a force of which the amount is termed their weight. Let us reflect how universally useful this power is. It holds everything in its place. It keeps one stone pressed down upon another, and thus makes building practicable. Bodies that have little gravity, or that are light, possess little stability and are readily tossed hither and thither. Our bones and muscles, and the strength of plants and all other terrestrial materials are adjusted to the strain which gravity makes upon them. By the steady permanence of its laws the ship floats safely upon the water, and the balloon soars safely into the air. It is gravity which enables us to balance ourselves in walking, running or riding. By the adjustment of their gravity to the medium in which they are placed birds fly and fishes swim. In short there is no limit to the conveniences and benefits we derive from this "Power of the Lord.”

Another Power essential to our well-being is Friction, which, in conjunction with gravity, regulates physical movement. It is the force that opposes displacement, which keeps things steady, and finally brings them, if in motion, to a state of rest. With every kind of movement some frictional opposition will always be found at work tending to stop its continuance. It may be the rough surface of the ground, or the comparatively unresisting water, or the still more yielding air, but each with varying degrees of frictional energy ultimately subdues the moving force, and sets the body at rest. Many are the attempts ingenious man has made to overcome this difficulty, but the search after "perpetual motion" is ever baffled by omnipresent friction, and the greatest success is measured only by the gain implied in substituting a friction that is less for one that was more.

Thus we oil axles and hinges, to diminish the rubbing opposition. Thus wheels were invented to escape in some degree from friction by rolling over the rough ground instead of scraping across it. So, also, by gradual improvement rude tracks were changed into smooth, macadamised roads, and these last in their turn are yielding to the even rail. Every new success has been merely the lessening of friction.

In these and in many other ways friction may be said to create difficulties which man's ingenuity partially enables him to overcome, but let us for a moment try to realise what would have happened if there had been no such Power in existence. When a surface offers little friction we call it slippery; and ice, though offering resistance sufficient to bring a skater or a stone gradually to rest, is yet remarkable for the comparative absence of friction. What occurs? In venturing upon it most persons find their movements difficult to control even when the surface is level, but they find it impossible to regulate them at all when ice is upon the slope. Now if there were no such thing as friction, land would be as slippery as ice. Without mechanical support it would be impossible to ascend a hill. Horses could not keep their feet against a strain; everything we handled would slip through our fingers with eel-like glibness. Quiescence and steadiness would be banished from the world, and objects once set in motion would go on without stopping until brought up by some equal opposing force. Thus it may be perceived that the friction of matter steadies and assists us in almost every act we perform; and, without its aid, the innumerable combined movements of every day life would be impossible. "Without this property," says Dr Whewell, "apartments, if they kept their shape, would exhibit to us articles of furniture and of all other kinds sliding and creeping from side to side at every

push and at every wind, like loose objects in a ship's cabin, when she is changing her course in a gale."

Yet our daily life shell is all that is

In sauntering among the scenes of this solid-looking world, how few there are who ever bestow a thought upon the Powers enchained within it. is spent over an abyss, and a mere thin interposed between us and destruction. As the crust of the earth is pierced the temperature is found to increase about a hundred degrees for every mile of depth; and consequently, if this ratio be maintained, thirty or forty miles beneath our feet there is a heat so intense that all substances with which we are acquainted must exist in a state of fusion. Great though this depth may at first sight appear, it is only a hundredth part of the space interposed between us and the earth's centre; and, if we were to imagine the globe represented by an egg, the shell would be comparatively much thicker than the thin layer which forms the earth's crust. Far down in the mysterious caverns of this crust, the molten rocks, the incandescent vapours, and bursting gases, are ever battling together and struggling with inconceivable force to rend their prison walls. Sometimes we hear with awe the distant thunder of the conflict, and sometimes the foundations of the earth itself tremble or are torn asunder. Those are the regions where fierce chaos is mercifully held down by the weights which God has heaped upon it; but, be it remembered, the Power is there, and is ready, if the word be spoken, to burst forth and in an instant drown this fair world in waves of molten fire, and burn it into ruin. In this internal crucible were compounded in olden time the granites, the porphyries, and the basalts which, after forcing their way through overlying strata, consolidated themselves, lava-like, into rocks and mountains. The convulsions of the young world must have been truly awful, for in every country the rocks to this

day bear testimony to the violence they then sustained. Many strata have been started from the bed on which they were gently and evenly deposited as a sediment, and have been cracked, splintered, or tilted over in all directions. Sometimes the fiery giant, unable to burst completely through, has lifted the strata over him until they rose into ridges, or, by causing partial upheavals and subsidences, has produced those dislocations or "faults" which are now so perplexing to the miner. Nor are the chymical marks of the heat less evident than those of the violence which attended it. Sometimes the soft sandstone touching the fiery stream has been fused into quartz, or indurated into a flinty hardness which shades off into the natural texture of the rock as it recedes from the point of contact. Occasionally the glowing stream baked the contiguous clay into coarse porcelain. The chalk and the limestone, instead of being changed into quicklime, as would have happened had they been calcined in the open air, have been fused into crystalline marble, such as is quarried at Carrara, from their having been heated under the pressure of superjacent strata. Owing to the same cause shales are found occasionally converted into hard, porcellaneous jasper, while seams of coal are coked or charred from their proximity to the igneous rock.

Although internal igneous action is happily now restrained within more moderate bounds, yet have we sure proof in the volcano and earthquake that subterranean fires do still possess much of their ancient fury. At never distant intervals Vesuvius, Etna, and Hecla heave up their lavas from depths that lie beyond our power to explore, and during the spring of 1866, a volcano burst forth in the harbour of Santorin. The great centres of igneous action, however, are now to be found on the Andean side of South and Central America,