motions, he did not yet possess any evidence that such a force actually
resided in the sun and planets. The failure of his former attempt to
identify the law of falling bodies at the earth's surface with that which
guided the moon in her orbit, threw a doubt over all his speculations, and
prevented him from giving any account of them to the public.

An accident, however, of a very interesting nature induced him to resume
his former inquiries, and enabled him to bring them to a close. In June,
1682, when he was attending a meeting of the Royal Society of London, the
measurement of a degree of the meridian, executed by M. Picard in 1679,
became the subject of conversation. Newton took a memorandum of the result
obtained by the French astronomer, and having deduced from it the diameter
of the earth, he immediately resumed his calculation of 1665, and began to
repeat it with these new data. In the progress of the calculation he saw
that the result which he had formerly expected was likely to be produced,
and he was thrown into such a state of nervous irritability that he was
unable to carry on the calculation. In this state of mind he intrusted it
to one of his friends, and he had the high satisfaction of finding his
former views amply realized. The force of gravity which regulated the fall
of bodies at the earth's surface, when diminished as the square of the
moon's distance from the earth, was found to be almost exactly equal to the
centrifugal force of the moon as deduced from her observed distance and
velocity.

The influence of such a result upon such a mind may be more easily
conceived than described. The whole material universe was spread out before
him; the sun with all his attending planets; the planets with all their
satellites; the comets wheeling in every direction in their eccentric
orbits; and the systems of the fixed stars stretching to the remotest
limits of space. All the varied and complicated movements of the heavens,