Theory of the Pneumatic Paradox. 



299 



attempted to explain the phenomenon, with the exception of Mr. 

 Allies, to seek some other cause of it. This gentleman, unwil- 

 ling to relinquish the idea of rarefaction, regards the adhesion of 

 the disks as a particular case of a general principle which he de- 

 duces from it, but which, as has been shown, may be demonstra- 

 ted to be false. There still remains, therefore, the principal diffi- 

 culty, of which I now proceed to offer a solution. 



For the leading ideas contained in it, I am mdebted to the late 

 Samuel Abbot, Esq., of Wilton, N. H. The experiment was de- 

 scribed to him in June, 1828, by O. W. B. Peabody, Esq., now 

 of this city, during the session of the Legislature of the State of 

 New Hampshire, of which they were then both members. After 

 a little reflection, he suggested to Mr. Peabody, and subsequently 

 to me, substantially the following explanation. 



Fig. 1. 



Let the accompanying figure represent the space between the 

 two disks, O its centre, AAN the circumference of a circle of the 

 same diameter as the tube to which the fixed disk is adapted, 

 and corresponding to the tube when the two disks are applied to 

 each other. Let the distance of the two circles AA, BB from 

 each other, be equal to that of the two, BB, CC. On blowing 

 through the tube, the air radiates in all directions from the circle 

 AAN. As any portion of air recedes from the centre, that, for 

 instance, which at one moment occupies the space AA, BB, it 



