oposals
for that purpose, and to grant sums of money not exceeding 2000L. to
aid in such experiments. It will be remembered from what has been
above stated, that a reward of 10,000L. was to be given to the person
who should contrive a method of determining the longitude within one
degree of a great circle, or 60 geographical miles; 15,000L. within 40
geographical miles; and 20,000L. within 30 geographical miles.

It will, in these days, be scarcely believed that little more than a
hundred and fifty years ago a prize of not less than ten thousand
pounds should have been offered for a method of determining the
longitude within sixty miles, and that double the amount should have
been offered for a method of determining it within thirty miles! The
amount of these rewards is sufficient proof of the fearful necessity
for improvement which then existed in the methods of navigation. And
yet, from the date of the passing of the Act in 1714 until the year
1736, when Harrison finished his first timepiece, nothing had been done
towards ascertaining the longitude more accurately, even within the
wide limits specified by the Act of Parliament. Although several
schemes had been projected, none of them had proved successful, and the
offered rewards therefore still remained unclaimed.

To return to Harrison. After reaching his home at Barrow, after his
visit to London in 1728, he began his experiments for the construction
of a marine chronometer. The task was one of no small difficulty. It
was necessary to provide against irregularities arising from the motion
of a ship at sea, and to obviate the effect of alternations of
temperature in the machine itself, as well as the oil with which it was
lubricated. A thousand obstacles presented themselves, but they were
not enough to deter Harrison from grappling with the work he had set
himself to perform.

Every one knows the beautiful machinery of a timepiece, and the perfect
tools required to produce such a machine. Some of these tools Harrison
procured in London, but the greater number he provided for himself; and
many entirely new adaptations were required for his chronometer. As
wood could no longer be exclusively employed, as in his first clock, he
had to teach himself to work accurately and minutely in brass and other
metals. Having been unable to obtain any assistance from the Board of
Longitude, he was under the necessity, while carrying forward his
experiments, of mainta