Theory of the Pneumatic Parador. 297 
being of a higher temperature than the surrounding air. This 
explanation is set aside by the fact, that if a pair of bellows be 
used instead of the lungs, the experiment succeeds equally well. 
Another explanation published in his youth by Charles G. Page; os 
M. D., a gentleman well known to scientific readers, both in this = 
country and in Enrope, for his inventions and discoveries in elec- 
tro-magnetism and magneto-electricity, originally communicated 
to this Journal, ascribes the phenomenon to currents of air which 
strike against the movable disk nearly at right angles to its plane, 
and which give it a tendency to adhere to the fixed disk. He 
demonstrated the existence of these currents, by admitting into a 
darkened room through a hole in the shutter, a beam of light, 
and scattering a little dust in the beam, so that the direction of 
any currents of air might be indicated by the motions of the par- 
ticles of dust. These currents are caused by the air which issues 
from between the disks, carrying with it some of the contiguous 
air, into the place of which they rush nearly at right angles with 
the disk. They are evidently inadequate to cause the adhesion 
of the disks, since they cannot have a momentum greater than 
that of the aforesaid contiguous air, which is much inferior to 
that of the original blast. That they are not essential to the 
adhesion of the disks, may be demonstrated by the following ex- 
periment. Make of thin letter paper a hollow cylinder, of the 
same diameter as the disks, eight or ten inches long, and tight at 
both ends. - Upon the mouth of a jar place a cover having a cir- 
cular hole large enough to admit the cylinder without friction, 
and through’ this hole sink the cylinder till it projects but little 
above the cover. On applying the fixed disk to the superior base 
of the cylinder, and blowing with a strong and long continued 
blast through the tube, the cylinder may, against its own gravity, 
be raised from the bottom of the jar, and even be lifted entirely 
out of it. In this case it is obvious that the cylinder cannot be 
sustained by currents underneath, and, of course, that such cur- 
rents cannot be essential to the adhesion of the disks. "The same 
thing may be likewise shown in the following manner. Leta 
newspaper be pasted to a table by the edges in such a manner 
as to occasion no tension, and, on applying the fixed disk to the 
middle of it, and blowing strongly through the tube, that part of 
. the newspaper may be sensibly raised from the table. In this 
