hy Christian Huygens. ^09 
tioning that Galileo, in his old age, had added a pendulum to 
clocks, after adding the words of Becker and those of Magalotti, 
in the Experiments of the Academy del Cimento^ concludes thus : 
“ Lastly, We possess the letters of Galileo to Beaugrand, with 
others of Reaal and Hortensius, which, besides Viviani, prove, 
in an indubitable manner, that Galileo really made the applica- 
tion of the pendulum to clocks. It is Elia Deodati, who, in 
1637, sent an account to the father of the celebrated Huygens^ 
of the pendulum-clocks constructed by Galileo ; and Becker 
adds, that a model was likewise sent to Holland. All this is 
sufficient to refute Huygens, Musschenbrdek, and many others^ 
^vho will not allow Italy the honour of these great discoveries*.” 
It is 'impossible to meet with more unqualified charges, and 
if, after the lapse of centuries, nothing should remain on the 
subject but the writings of Becker and of this eulogist, one 
would be compelled to refuse Huygens all share in the applica- 
tion of the pendulum, and perhaps to refer it to an earlier pe- 
riod than Galileo himself, — so difficult it is sometimes to ascer- 
tain the truth in the history of science. What, then, are we to 
think of the opinions of older philosophers, as described by his- 
torians, panegyrists, and other writers, when such uncertainty 
exists respecting a discovery a little more than one century and 
a half old? 
To these bold assertions I shall now oppose the evidence of 
Jhcts^ which I have arranged under the five following heads : 
In the first place. By showing that the correspondence of 
Galileo contains not a word of the pretended application of the 
pendulum to clocks. 
Secondly^ By disproving, what is hinted at, that Huygens 
learnt the application made by Galileo through the letters of his 
father, or by a model from Italy. 
Thirdly^ By exhibiting, what has never been done yet, the 
actual clock, as devised or made by Galilei and his son Vicen- 
zio, from papers hitherto unpublished, and shewing that Huy- 
• This work on Galileo has been literally copied in the Geneva edition of the 
Encyclopedic^ in quarto, by Pellet, and the octavo edition, under the word Galileo, 
where it is attributed to Frisi, This is false ; the Elogio dc Galileo by Frisi, of 
which more hereafter, is a totally diiTerent work, and contains altogether different 
views from those here expressed. 
