out
its spear-like wings at every alarm, like its predecessor of the lower
formation. Fish still remained the lords of creation, and their bulk, at
least, had become immensely more great. We began with an age of dwarfs,
we end with an age of giants, which is carried on into the lower coal
measures. We pursue our history no further?

Has the last scene in the series arisen? Cuvier asked the question,
hesitated, and then decided in the negative, for he was too intimately
acquainted with the works of the Creator to think of limiting His power,
and he could anticipate a coming period in which man would have to
resign his post of honour to some nobler and wiser creature, the monarch
of a better and happier world.

SIR ISAAC NEWTON

Principia

Sir Isaac Newton was born at Woolsthorpe, Lincolnshire, England,
Dec. 25, 1642, the son of a small landed proprietor. For the famous
episode of the falling apple, Voltaire, who admirably explained his
system for his countrymen, is responsible. It was in 1680 that
Newton discovered how to calculate the orbit of a body moving under
a central force, and showed that if the force varied as the inverse
square of the distance, the orbit would be an ellipse with the
centre of force in one focus. The great discovery, which made the
writing of his "Philosophiae Naturalis Principia Mathematica"
possible, was that the attraction between two spheres is the same
as it would be if we supposed each sphere condensed to a point at
its centre. The book was published as a whole in 1687. Of its
author it was said by Lagrange that not only was he the greatest
genius that ever existed, but also the most fortunate, "for we
cannot find more than once a system of the world to establish."
Newton died on March 20, 1727.

Our design (writes Newton in his preface) not respecting arts but
philosophy, and our subject not manual but natural powers, we consider
those things which relate to gravity, levity, elastic force, the
resistance of fluids and the like forces, whether attractive or
impulsive; and, therefore, we offer this work as the mathematical
principles of philosophy, for all the difficulty of philosophy seems to
consist in this--from the phenomena of motions to investigate the forces
of nature, and from these forces to demonstrate the other phenomena, and
to this end the general propositions in the first and second b