portance of the theory of universal
gravitation made its general acceptance a matter of considerable time
after the actual discovery. This opposition had of course been foreseen
by Newton, and, much as he dreaded controversy, he was prepared to face
it and combat it to the bitter end. He knew that his theory was right;
it remained for him to convince the world of its truth. He knew that
some of his contemporary philosophers would accept it at once; others
would at first doubt, question, and dispute, but finally accept; while
still others would doubt and dispute until the end of their days. This
had been the history of other great discoveries; and this will probably
be the history of most great discoveries for all time. But in this case
the discoverer lived to see his theory accepted by practically all the
great minds of his time.

Delambre is authority for the following estimate of Newton by Lagrange.
"The celebrated Lagrange," he says, "who frequently asserted that Newton
was the greatest genius that ever existed, used to add--'and the most
fortunate, for we cannot find MORE THAN ONCE a system of the world to
establish.'" With pardonable exaggeration the admiring followers of the
great generalizer pronounced this epitaph:

"Nature and Nature's laws lay hid in night;
God said 'Let Newton be!' and all was light."

XIII. INSTRUMENTS OF PRECISION IN THE AGE OF NEWTON

During the Newtonian epoch there were numerous important inventions of
scientific instruments, as well as many improvements made upon the older
ones. Some of these discoveries have been referred to briefly in other
places, but their importance in promoting scientific investigation
warrants a fuller treatment of some of the more significant.

Many of the errors that had arisen in various scientific calculations
before the seventeenth century may be ascribed to the crudeness
and inaccuracy in the construction of most scientific instruments.
Scientists had not as yet learned that an approach to absolute accuracy
was necessary in every investigation in the field of science, and that
such accuracy must be extended to the construction of the instruments
used in these investigations and observations. In astronomy it is
obvious that instruments of delicate exactness are most essential; yet
Tycho Brahe, who lived in the sixteenth century, is credited with
being the first astronomer whose instruments show extreme care in
construction.

It seems practica