46 M. Van Swinden on the Invention of Fendnlum-Chchs 
that Galileo had, indeed, in 1641, proposed the application of 
pendulums to clocks, that his son had endeavoured, with the 
assistance of one Dominico Balestri of Florence, to put it into 
practice; but that his death (which happened in 1649, eight years 
after his father’s) had prevented him from seeing it executed, 
and that only several years afterwards Trefler had accomplished 
it, though somewhat in a different way from what he had in- 
tended. ” (Tiraboschi, p. 155.) The accounts which these 
writers have left us of the clock in question, go a great way to 
strengthen a suspicion, that it was either wholly made after the 
construction of Huygens, or altered, in so far as respects the 
pendulum. Frisi says in aS many words, that except the spring- 
barrel and fusee, the disposition of the wheels was exactly the 
same as in the clocks made by Huygens ; it had likewise the bent 
plates or checks, which, whether cycloidal or not, are unques- 
tionably an invention of Huygens. Frisi allows the work to be 
his, and Perelli admits the curved plates to be an addition of a 
later date, and Brenna, after acknowledging the same, seems 
very much puzzled how to account for the rest. It is quite" 
possible that an existing clock should have been altered by 
Trefler, and a pendulum adapted to it after the manner of 
Huygens ; many examples occur of the same, as we shall pre- 
sently see. But I must first remark bn the improbability, that 
if Trefler had really made a pendulum-clock, and a good one, 
on principles of construction discovered either by himself or the 
Galileos before Huygens, these clocks should have been so little 
known in Italy, at Rome, even at Florence itself, as they appear 
to have been at the period of Huygen’s work becoming known 
in those parts of Europe. The letters among the Leyden 
MSS. leave no doubt on that head. We find from Bouillau’s 
letters, that it was first sent to Florence in the autumn of 
1658 ; on the other hand, we learn, from the words of Prince 
Leopold, communicated by that gentleman to Huygens, half a 
year later, and which have already been given, that after three 
years’ attention to the subject, an artist had made one, which he 
hoped would succeed. Now, we may ask, why this doubtful 
language, and why these attempts, of the issue of which they 
confessed themselves uncertain, if Trefler had already accom- 
plished the construction, and it had proved to be good ? There 
