S.- 
= . ie ‘ 
* 
_ On the P tic Paradox. 145 
tions of recent date, I was led, without further inquiry, to describe 
as hew, several results, which, as I have since learned, had been 
previously discovered. Mr. Hopkins, and, previously to him, 
Mons. Clément-Désormes, in a memoir presented to the French 
Academy of Sciences, have anticipated me in proving the exis- 
tence of a partial vacuum between’the disks, An-account of 
some experiments by Dr. Faraday, for a knowledge of which I 
am indebted to Prof. Henry, is contained in the third volume of 
the Quarterly Journal of Science, and among them are two or 
three similar to some of the Jess important jones described by me. 
Thus far I feel called upon to disclaim any pretensions to priority 
of discovery. nostic! zieo-ede 1 Ba eseead 
All of these gentlemen, if I understand them aright, attribute 
the adhesion of the disks solely.to:what I have :called. the pri- 
mary rarefaction, produced by the lateral expansion of:-the.radi= 
ating currents, in consequence of their “ passing ‘froma smallei' to 
a larger space.” From their failure to‘ distover-what I shave: 
termed the secondary rarefaction, the theory: adopted by‘ threni’ 
seems to me essentially.defective.. Itiaffords no’explaration of: 
the fact that, as the experiment is usually performed, the diris rare-! 
fied inward to the very orificeof - ~  - ork 
the tube, where no expansion of 
the radiating currents can have 
taken place, and, in certain cir- 
cumstances, four inches and a 
half into the tube itself, ‘The 
latter singular result was obtain- 
ed in the following manner. 
To the perforated center of a 
Plate of tinned sheet. iron was 
soldered, as represented in the : 
“ccompanying figure,- a tube : 
eight inches long, anda quarter 
an inch in diameter. Holes 
were made at intervals in it, 
and to them were soldered small 
leaden tubes, a few inches long, 
'o which a glass tube, bent in 
the form of a double syphon, #———___4. L___—_—__— 
could readily be adapted, Only 
Vol. x, No, 1.—Oct.Deec. 1840, 19 
4 
