Truth

triumphant.

Isaac Newton.

why relate the painful tale of the rigorous examinations, and the recantation finally forced upon the feeble old man? In the year 1642 the shattered body of the philosopher was laid to rest, but in unconsecrated ground, for the iron heel of the Inquisition must even grind his bones! Many of his manuscripts were destroyed, and his friends were not permitted to raise a monument in his honor.

But the truth, which had thus been ruthlessly trampled under foot, beneath the blue skies of fair Italy, rose in adamantine strength amid the sturdy oaks of old England. On Christmas Day of the year in which Galileo died there was born a boy who was to supplement the work not only of Galileo, but also of Copernicus, Tycho, and Kepler, and to be recognized as the master mind among the world's philosophers.

Isaac Newton was not a very promising lad, until the day when a bigger boy conferred a signal blessing on the world by kicking him. Young Isaac retorted by thrashing his assailant, and then proceeded to show the rest of the boys at school that he could beat them in their studies. So keen became his interest in books that he was sent to Trinity College, Cambridge, where his remarkable aptitude for mathematics displayed itself. We cannot recount all the marvelous researches to which Newton's genius lent itself. The discovery which concerns us at present is that of the law of gravitation.

Copernicus had proved that the planets revolved about the sun as a center. Tycho had observed with all assiduity, and Kepler, by discussing these observations, had discovered the three laws which bear his name. Galileo had not only enlarged astronomical knowledge by the use of the telescope, but had promulgated the laws of motion of bodies on the surface of

the earth. These laws were admirably restated by Newton, and are now called Newton's laws. But the Newton's laws. crowning glory of his achievements is the proof that the

sun.

gravitation.

same force which pulls the apple to the earth controls the motion of the moon, and binds the planets to the The law of This force is not constant in intensity, but varies inversely as the square of the distance. Kepler's laws have been proven to be necessary consequences of the

Its wide application.

law of gravitation. The entire mechanism of the planetary movements, not their elliptical paths alone, but also their small departures from true ellipses, caused by their

attractions for one another, are all explained by this simple law.

If Newton's law be correct, will not the mutual attractions of the planets so derange their orbits that at last

Laplace.

there will be wreck and ruin, where now are order and beauty? During the last century Lagrange and La- Lagrange and place, the most illustrious of French mathematicians, proved that though the orbit of each planet alters somewhat, changing in both shape and position, the disturbances are confined within narrow limits, and the system of planetary worlds is therefore stable.

We now bring our rough historical outline to an end, having come up to the close of the eighteenth century, when the construction of large telescopes by Sir William Herschel and others gave a special impetus to observational astronomy, and led to the unfolding of the science along new lines.

William

Herschel.

The arm-chair.

Bright stars.

CHAPTER II.

THE HEAVENS AND THEIR APPARENT DAILY REVO

The sad and solemn night

LUTION.

Has yet her multitude of cheerful fires;

The glorious host of light

Walk the dark hemisphere till she retires:

All through her silent watches, gliding slow,

Her constellations come, and climb the heavens, and go."

PERMIT the author to talk to you, the reader, for a moment. Perchance you are seated in an arm-chair, with your feet on the fender, and this book in your hands. You have vanquished Chapter I. and are ready for fresh victories. The next foe to be overcome is the arm-chair. For you will never take a deep interest in astronomy if you confine yourself to an arm-chair and a book. A young man rarely becomes enamored of a young lady into whose face he has never gazed. You must look into the eyes of the goddess Urania; they spangle the heavens, and will well repay your most ardent gazing. Surely you know the Great Dipper, which performs the endless round of motion about the north pole of the sky. But are you acquainted with Vega the beautiful, Arcturus the magnificent, Capella the icy, and Sirius the glowing? Why do we call Vega beautiful? When you have observed its hue, you will know. Why is Arcturus magnificent? If you shall be led to think that it is thousands of times as large as our sun, you will not begrudge it the adjective. In the dead