re solicitous to find a
way of determining the longitude that would be sufficiently correct.
Thus, the King of Spain, in 1598, offered a reward of a thousand crowns
to any one who should discover an approximately correct method. Soon
after, the government of Holland offered ten thousand florins. In 1714
the English government took hold of the matter, and offered a series of
dazzling prizes: Five thousand pounds for a chronometer that would
enable a ship six months from home to get her longitude within sixty
miles; seven thousand five hundred pounds, if within forty miles; ten
thousand pounds if within thirty miles. Another clause of the bill
offered a premium of twenty thousand pounds for the invention of any
method whatever, by means of which the longitude could be determined
within thirty miles. The bill appears to have been drawn somewhat
carelessly; but the substance of it was sufficiently plain, namely, that
the British Government was ready to make the fortune of any man who
should enable navigators to make their way across the ocean in a
straight line to their desired port.

Two years after, the Regent of France offered a prize of a hundred
thousand francs for the same object.

All the world went to watch-making. John Harrison, stimulated by these
offers to increased exertion, in the year 1736 presented himself at
Greenwich with one of his wonderful clocks, provided with the gridiron
pendulum, which he exhibited and explained to the commissioners.
Perceiving the merit and beauty of his invention, they placed the clock
on board a ship bound for Lisbon. This was subjecting a pendulum clock
to a very unfair trial; but it corrected the ship's reckoning several
miles. The commissioners now urged him to compete for the chronometer
prize, and in order to enable him to do so they supplied him with
money, from time to time, for twenty-four years. At length he produced
his chronometer, about four inches in diameter, and so mounted as not to
share the motion of the vessel.

In 1761, when he was sixty-eight years of age, he wrote to the
commissioners that he had completed a chronometer for trial, and
requested them to test it on a voyage to the West Indies, under the care
of his son William. His requests were granted. The success of the
chronometer was wonderful. On arriving at Jamaica, the chronometer
varied but four seconds from Greenwich time, and on returning to England
the entire variation was a little short of two mi