64 Le Roy’s Memoir on the best Method 
said with regard to the pendulum is evidently applitable 
here, since we have seen, Article II., that supposing the 
vibrations of the free balance isochronous in its application 
to the watch, the Jong arcs, which arise from>less friction 
upon the pivots, would make it advance ; but if they pro 
ceed from an overplus of motive force, they retard it, on the 
contrary ; and that the difficulty of the action of the wheel- 
work would produce again a different effect, &c. - 
What will it be if we introduce the changes which arise 
in the magnitude of the vibrations from shocks and divers. 
motions? By a little attention we shall find that an escape- 
ment can never render the vibrations isochronou’ in these 
different cases, unless it be a true Proteus, whose form, con- 
tinually varying, adapts itself to these different circumstances. 
I shall say on this occasion, that notwithstanding the ex 
periments made with the time-keepers of Mr. Harrison, 
which are so strongly in favour of this work, the methods 
which are used to render the vibrations of the regulator iso- 
chronous appear to me very imperfect, and that I am here 
of the same opinion as the person who has made the report 
to the Board of Longitude. Supposing, says he, the opinion 
of Mr. Harrison to be true, (he speaks of the short vibra* 
tions which Mr. Harrison pretends are slower than the long,) 
Tam by no means certain, continues he; that the methods he 
employs are proper to produce the effect which he expects 
from them. In truth; this article of the report appears to 
me absolutely unintelligible. Mr. Harrison uses, says the 
report, ¢wo methods to render the motion of the vibrations 
egual: the first is, to put a pin, against which the balance 
may press, which augments its force; but it is found to be 
diminished, as Mr. Harrison pretends, when the vibrations 
are greater. The second method is, to give to his pallets 
such a form, that the wheels may press them less when the 
vibrations augment. Although the terms of this Report are 
not very intelligible, and appear even incomprehensible, 
since it mentions wheels which press less when the vibra- 
tions aligment, instead of which, by the description, there 
isa very delicate spring which acts on the balance by one 
wheel only; we may nevertheless suspect that the isochro- 
nism 
