ining himself by still working at his trade of a
carpenter and joiner. This will account for the very long period that
elapsed before he could bring his chronometer to such a state as that
it might be tried with any approach to certainty in its operations.

Harrison, besides his intentness and earnestness, was a cheerful and
hopeful man. He had a fine taste for music, and organised and led the
choir of the village church, which attained a high degree of
perfection. He invented a curious monochord, which was not less
accurate than his clocks in the mensuration of time. His ear was
distressed by the ringing of bells out of tune, and he set himself to
remedy them. At the parish church of Hull, for instance, the bells
were harsh and disagreeable, and by the authority of the vicar and
churchwardens he was allowed to put them into a state of exact tune, so
that they proved entirely melodious.

But the great work of his life was his marine chronometer. He found it
necessary, in the first place, to alter the first mover of his clock to
a spring wound up, so that the regularity of the motion might be
derived from the vibrations of balances, instead of those of a pendulum
as in a standing clock. Mr. Folkes, President of the Royal Society,
when presenting the gold medal to Harrison in 1749, thus describes the
arrangement of his new machine. The details were obtained from
Harrison himself, who was present. He had made use of two balances
situated in the same plane, but vibrating in contrary directions, so
that the one of these being either way assisted by the tossing of the
ship, the other might constantly be just so much impeded by it at the
same time. As the equality of the times of the vibrations of the
balance of a pocket-watch is in a great measure owing to the spiral
spring that lies under it, so the same was here performed by the like
elasticity of four cylindrical springs or worms, applied near the upper
and lower extremities of the two balances above described.

Then came in the question of compensation. Harrison's experience with
the compensation pendulum of his clock now proved of service to him.
He had proceeded to introduce a similar expedient in his proposed
chronometer. As is well known to those who are acquainted with the
nature of springs moved by balances, the stronger those springs are,
the quicker the vibrations of the balances are performed, and vice
versa; hence it follows that those springs, when