small bodies rush towards large ones, and the stars of lesser magnitude revolve round the stars of greater magnitude, is an impenetrable mystery to mankind. Whatever may be the hypothesis by which we seek to explain the fact, it is certain that the sun holds the planets with their satellites, the asteroids and the comets, suspended above the abysses of space, and that they journey through the heavens in unintermitting obedience to his guiding influence. The sun draws with him all the stars which follow and surround him, like flatterers of his power, like humble slaves of his universal preponderance. Like the father of a family in the midst of his progeny, the sun peacefully governs the numerous children of sidereal creation. Obedient to the irresistible impulsion which emanates from the central star, the earth and the other planets circulate, roll, gravitate, around him, receiving light, heat and electricity from his beneficent rays, which are the first agents of life. The sun marks out for the planets their path through the heavens, and distributes to them their day and night, their seasons and their climate. The sun is, then, the hand which holds the stars above the unfathomable abysses of infinite space, the centre from which they obtain heat, the torch which gives them light, and the source whence they derive the principle of life. From all time the immense and unique task fulfilled by the sun in the economy of nature has been understood. But this great truth has only been deeply studied in our days. Science has gone far beyond all the imagination the poets had conceived relative to the preponderance of the sun in our world. By means of numerous experiments and abstruse calculations, modern physicists have proved that the sun is the first cause of almost all the phenomena which take place on our globe, and that, without the sun, the earth and no doubt all the other planets would be nothing but immense wastes, gigantic corpses, rolling about, frozen and useless, in the deserts of infinite space. Professor Tyndall, who has added largely to the discoveries of physics and mechanics, has brought out this truth very strongly, and the results to which he has been led may be said to form the most brilliant page of contemporary physical science. We shall now endeavour to explain how it is that everything on the earth, and no doubt on all the other planets also, is derived from the sun, so entirely, that we may affirm that vegetables, animals, man, in short, all living beings, are but the productions, the children of the sun; that they are, so to speak, woven out of solar rays. In the first place, the sun is the primary cause of all those movements which we observe, in the air, in the water, or in the ground under our feet, and which keep up life, feeling, and activity on the surface of our globe.