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 braced by cold, or when relaxed by heat, must
of necessity cause the timekeeper to go either faster or slower,
unless some method could be found to remedy the inconvenience.
The method adopted by Harrison was his compensation balance,
doubtless the backbone of his invention. His "thermometer kirb,"
he himself says, "is composed of two thin plates of brass and
steel, riveted together in several places, which, by the greater
expansion of brass than steel by heat and contraction by cold,
becomes convex on the brass side in hot weather and convex on the
steel side in cold weather; whence, one end being fixed, the
other end obtains a motion corresponding with the changes of heat
and cold, and the two pins at the end, between which the balance
spring passes, and which it alternately touches as the spring
bends and unbends itself, will shorten or lengthen the spring, as
the change of heat or cold would otherwise require to be done by
hand in the manner used for regulating a common watch.
Pages:
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130