Meddelelser 2008 - Ole Rømers Venner

This conclusion is relevant in dealing with Huygens' efforts to apply his new
invention in timekeepers to be used at sea, as was explicitly mentioned in the patent
and in his publication. Already in a letter to Oldenburg dated I I July 1675, he admits
that, although he considers the new watches incomparably better than the ordinary
onest their accuracy is less than of clocks with a pendulum, particularly a long
pendulum.sl As is also clear from other letters, the balance spring construction
appeared to be rather sensitive to movements. Huygens had tried to remedy this by
introducing a second balance rotating in the opposite direction, but this required too
much force. He concludes his comments in the letter to Oldenburg with the
announcement of a more simple solution which he is testing now with perfect
success. Probably he referred to his doubling of the number of revolutions from 120
to 240 per minute mentioned in a subsequent letter to Oldenburg.s4
Huygens'correspondence in the following years does not mention any effort to apply
the spring balance in timekeepers for measuring longitude at sea. This silence does
not necessarily means that he was not involved. Soon after its invention, he tried out
experimentally the effect of temperature and observed tha! after heating the spring
considerably, the vibrations of the balance were not slower than with the cold
spring.s5 In his Memoire concernant I'Åcademie Royale des Sciences, written in 1679,
we read that
because the pendulum clocks necessarily suffer from the ship movements, there is
more hope to succeed with balances with a spiral spring, but constnrcted in a large
size because the accuracy is believed to depend on the dimension ['la justesse croit a
mesure'], and it would be very worthwhile to do this experiment."s6
Three years later, he writes that
after the tests I have recently made, I venture to promise clocks just as accurate as our
long pendulums by means of my invention of the spiral spring which can easily resist
the largest movements of the sea."
ZE