EXPERIMENTS AND OBSERVATIONS 



OK 



OF 



COMPRESSED AIR. 



BY MR. T. HOPKINS. 



(Read Not< 28, 1828.} 



\JN the eleventh of October, m the year 1824, 

 Mr. Roberts affixed a valve to the aperture of a 

 pipe, used as a waste-pipe, for the purpose of 

 regulating or equalizing the force of a blast 

 of air which was blowing a furnace. To his 

 surprize, however, he found that the valve, 

 instead of being readily blown off by a strong 

 blast, remained at a small distance from the 

 aperture of the pipe, and was removed to a 

 greater distance only by a considerable exer- 

 tion of the power of the hand. This singular 

 phenomenon was witnessed by many gentle- 

 men, members of this society, in the same week. 



