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are, however, more astonishing than are the tremendous facts which they are intended to explain; but in the present state of science all are to be looked upon as bare hypotheses. But whatever may be the real origin of the sun's heat, it is certain. that he is the fountain whence comes our own supply, and the cause of all the phenomena to which the action of heat gives rise on our earth. Thus, to the power of his calorific rays must be attributed the evaporation of water from the surface of the sea; the formation of winds, by which the moisture in the air is borne along until, coming in contact with lofty mountains, or with cooler strata of the atmosphere, it becomes condensed into clouds, and finally descends as rain upon the earth, where, mingling with the waters of the rivers, it at last reaches the ocean, and is ready to enter upon its round again. According to the doctrines of modern physics, heat and mechanical work are convertible, and it might prove interesting to enter upon calculation of the amount of work performed by the solar heat in the production of the circulation above described. We could estimate the work done in the conversion of the water into aqueous vapor, in the elevation of this vapor into the atmosphere, in its subsequent condensation, and descent back from the clouds to the ocean, including in the latter all the useful purposes to which it may have been applied by the ingenuity of man: the sum total would represent the work performed by the water in its entire circuit, and would give us a fair indication of the mechanical efficiency locked up in the heat rays of the sun. Our author, Mr. Proctor, has made this calculation for us, and, according to his estimate, 'the force expended in the production of a day's steady rain over an area equal to that of the county of Middlesex, England, is equivalent to a mechanical power that would be competent to raise 1,000,000,000 tons to a height of three miles.' What must be the total amount of energy stored away in the solar rays may be inferred when we reflect that the county of Middlesex constitutes but a minute fraction of the entire surface of the earth, and that the amount of heat received by the earth is but one ten thousand millionth of the entire quantity radiIated by the sun. And we must consider that the circuit of

the rains is not the only mechanical office performed by the solar heat. To the operation of this agency must also be attributed those grand systems of atmospheric and oceanic circulation which give rise to the trades and anti-trades, the monsoons, the gulf stream, and other 'rivers in the ocean 'systems which exercise so beneficial an influence over the climates of western Europe and America, and which require, for their production, an expenditure of energy well-nigh incalculable.

Equally important with the influence exerted by the heat. and light-rays of the sun is that of the so-called chemical or actinic rays; and it is highly probable that from these rays, which possess but little thermometric or illuminating power, are derived the greatest part of the energies manifested in the animal and vegetable worlds. It is under the powerful influence of these rays that plants are enabled to absorb carbonic acid from the air around them, assimilating the carbon, and setting free the oxygen, that great life-sustainer of the animal kingdom. They likewise, under the same influence, take in water and ammonia, and from these, with the aid of small quantities of mineral matter derived from the earth, they elaborate those highly organized compounds which form the chief subsistence of man and the lower animals. We thus see that to the solar rays are due the vital energies of all living beings; and when these energies are exerted, either in the involuntary act of living, or in the production of mechanical work, we are only giving back to the earth that which was first extracted from her by the operation of the sun's chemical forces. Again, these chemical rays not only provide the force by which the circuit of matter from the mineral, through the vegetable, to the animal, and back again to the mineral condition is produced and maintained, but they also provide for us the sources from which we derive our artificial heat and light. Carbon, in some or other of its various forms, is the substance by whose combustion heat and light are evolved. Whether we obtain this material from the wood of our forests, from the oils extracted from the monsters of the deep, or from the beds of coal which lie buried beneath the earth's surface, in every case are

Proctor, be his estimat

's steady!

iddlesex, Er

ould be co hree miles'

d away in t t the countr

the entire s

received by t
entire quat

er that the

5

we utilizing force derived, in the first instance, from the chemical activity of the solar rays. And when we convert the heat so obtained into mechanical work, we are, so to speak, only consuming the solar force which had been previously stored up for us in the organisms which have furnished to us the carbon we are burning.

We are thus led to the conclusion that all the various manifestations of physical force on the earth have their origin in the sun. In him we find the source of the regular motion of our planet in its orbit; to the tremendous energy of his rays are due the soft breezes and the gentle rains, the terrible storms and tempests which sweep over the face of the earth, the mighty movements of the sea and the air, by which the heat concentrated in the great equatorial reservoirs is distributed to the remotest corners of the globe; from him emanates that mysterious influence by which the mineral constituents of the earth are transformed into living organisms; he supplies to man those abundant stores of force which enable him to satisfy his daily needs, to build houses, to level mountains and fill up valleys, to make for himself highways along which he can travel with the speed of the wind, and to build moving palaces in which he can traverse the seas without fear of wind And his store of force seems inexhaustible. True, philosophers have speculated as to the possibility of a diminution of the sun's energy, and have calculated that in the ages to come he must, of necessity, expend all that he possesses, until at length his strength shall be exhausted. But we have no evidence of any such diminution; the sun has not, in all his past history, lost one iota of his gravitating power; he shines as brightly now, and his rays are as intensely warm, as ever, while their chemical activity has not changed since man and animals and plants have dwelt upon the earth; and we have the fullest liberty to conclude that, however great may be the expenditure, there exists outside the sun some power which is fully adequate to maintain the supply. The sun, with his entire system of planets, is known to be moving rapidly through space, and space is boundless in extent; why may it not be that in his onward sweep he is constantly re

or wave.

ceiving from the vast fields of matter through which he passes, and with which he comes in contact, contributions of force sufficient to balance that which he loses by radiation? At first sight this hypothesis, which is a favorite one with many scientists, seems to place the whole universe under tribute to the sun; and this would accord well with the views of the old philosophers, who believed that the universe was made for man, that the only office of the sun was to give light by day, and that of the moon and stars to rule the night. But from our higher standpoint we behold, not our own sun and system only, but a multitude of suns, which no man can number, drifting through space, and, as we believe, supplying light and life to the planets which surround them, while their own stores of energy are being continually received from the nebulous or meteoric aggregations with which the interstellar regions are filled. This view of the subject is not mere conjecture. We have abundant reasons for believing that the whole boundless extent of space is occupied by matter, each particle of which is a centre of attractive and a repulsive force, and that the actions and reactions of these forces upon and against each other are abundantly adequate to produce all the manifestations of force with which we are familiar in our own system, and which we must believe to exist in all other systems throughout the universe. The amount of force in the universe is, then, limited only by the extent of space itself, and we cannot conceive of any limitation to the latter save by the power of that Being who called all things into existence. And the energy of the sun, tremendous though it be, is as inex haustible as the fountain from which it is derived. So long as time and space1 and matter and force shall endure - and they must endure until called back by the fiat of the Almighty Ruler of the universe into that nothingness from which they sprang into being at his word-so long will our sun, and the myriads of other suns, continue to exercise their controlling power, and to send forth their benign rays, bearing with them light and

1 We cannot admit that space was created, because, to our minds, it seems evident that it is, like God himself, uncreated, self-existent, and necessarily eternal.-ED.

me

heat and life to the worlds around them. And in all the various phenomena to which the operation of force gives rise, there is no diminution of force itself. There may be transformation or conversion of force from one form to another chanical force may be changed into heat, this into light or chemical activity, and this into electricity or vital action— but the amount of force, like the quantity of matter, in nature, . is unchangeable. As Professor Tyndall beautifully expresses it (and with this we close): To Nature nothing can be added, from Nature nothing can be taken away. . . . . Waves may change to ripples and ripples to waves; magnitude may be substituted for number, and number for magnitude; asteroids may aggregate to suns, suns may resolve themselves into flore and fauna, and flora and faunæ melt into air-the flux of power is eternally the same. It rolls in music through the ages, and all terrestrial energy the manifestations of life, as well as the display of phenomena are but modulations of its rhythm.'

ART. III.—1. Progrès de ia France sous le Gouvernement Impériale. Paris: Imprimerie Impériale. 1869.

2. Galignani's Paris Guide. Paris: A. & W. Galignani. 3. Notes from Paris. Edinburgh: Edmonston & Douglas.

1855.

A great, wealthy, and well governed city is one of the most stupendous monuments of human industry and genius upon which it is possible for us to gaze; and among all the leading cities of modern times the magnificent capital of France claims to be, in many respects, preeminent. It is the centre, not only of French, but of European, cultivation and refineFrom the days of Catherine de Medicis to those of the third Napoleon, it has been the ambition of the rulers of France to make Paris, as they grandly phrase it, the capital of the universe-the city of cities-the glorious dwelling

ment.