20S 
hy Christian Huygens. 
appears likewise to have been intent on the means of rendering 
its motion perpetual, and even to have endeavoured to connect 
it with his clocks : “ But,"” he adds, ‘‘ whilst working at them, 
and before they were completely finished, it happened that Huy- 
gens had in 1657 invented similar clocks, and published a de- 
scription of them in 1658.” {Machina Ccekstis^ip. 366.) In a 
manuscript paper in Huygens’s own hand, containing short re- 
marks on his principal discoveries, under the title of Anecdota, 
{Leydeii MSS.), he only says of Hevelius, that he had made 
attempts for himself : “ Hevelius sibi occoepit.” Hook appears 
likewise to have found out a means of rendering the motion of 
pendulums perpetual, but it was no application of them to re- 
gulate clocks. {HooFs Works in fol. p. 4.) Many, in short, 
sought after something, — Huygens alone hit upon the true prin- 
ciple. He was far from denying, however, that the loose or de- 
tached pendulums brought into use for astronomical purposes 
by Galileo, had suggested to him the use which might be made 
of them to regulate clocks, {Horologium^ p. 1.) ; nor did he con- 
ceal that the common balance-clocks prevalent at that time, had 
furnished the ground of the escapement, and that he only alter- 
ed them so far as was necessary to adapt them to the action of 
the new regulating principle. (Jhid. jp. 7.) 
The description given by Huygens of his clocks, as likewise 
the clocks constructed by him, or undfer his inspection, soon 
taught clockmakers here and elsewhere to substitute the pendu- 
lum for the balance in existing works. Many, however, did 
not succeed so easily*; and although Wallis wrote Huygens, 
{Leyden that, before receiving his description, he had 
seen in England a clock with a pendulum, which was, however, 
known to be of his invention, and added, in a subsequent letter, 
that several English watchmakers imitated them each in his way, 
from which it would appear, that, very soon after the invention, 
* The numerous letters of M. Petit, Intendant des Fortifications et Ingenieur 
du Roi, to M. Huygens, form an amusing part of the collection in the Leyden MSS. 
He could not for a long time succeed in fitting up a clock in his possession, so as 
to make it go; and though he wrote letter after letter for advice, and added weight 
after weight to move the wheels, his difficulties seemed rather to increase ; and he 
was for several years the most troublesome correspondent of Huygens, whom he 
professed to admire very much,’-— iV^ofe of the Translator. 
