a oe 
5 eg 
On the stopping of Astronomical Clocks. Q77 
p, thes 
este a vane of leather, and being quickly turned — 
cord, heat was readily excited ; several trials were made, 
in all of which, except one, when the density of the air 
was diminished, less heat was excited. In that, about 
* 4s fourteen fifteenths of the air was exhausted—notwithstand- 
ing this, the heat was greater within the receiver than 
without. In this instance pressure was applied as far as 
could be, and allow the spindle to turn rapidly, the ex- 
periment was afterwards repeated with the same appara- 
tus and gentle pressure, ~ the heat was much greater 
Without the receiver than w 
Upon considering all the experiments there appears 
tion, and the question eihitss is it wholly by pean 
_ Oris there any other cause? 
If the experiment should be repeated it would be well 
to ascertain that the spindles excited equal heat—that 
time be allowed for the air to leave the pores of the wood 
~—and that the density - the air in the receiver during 
the experiment be note 
Respect, — 
AMES T. WATSON. 
New-York, May 8, 1824. 
Art, eres the Son 8 of Astronomical Clocks ; by 
., Professor of Natural Philosophy, 
sity of oy sen 
5 on we bob of the pendulum when the two become o 
site to each other. The very minute quality of this’ ats 
ae force renders it difficult to conceive that it can so 
. a a tos stop 
it; and the following observations induce me to_ 
that in the cases which have beens explained, t 
— is very different 
ive a French clock with a ver ry heavy half-second 
cotmpenuatighaptndalam, & fitted with Lepaute’s dead beat 
ee A weight of one and a half pounds in de- 
e were connected by a brass rod, passing 
by 4 
reason to believe that air assists in exciting heat by fric- 
8 ore 
sone to be the attraction sinsech by the weight” 
