THE BALL-PARADOX. 



725 



gallantry, like his science, may be now a little out of date, but he 

 manages at least to unite these two most opposite conversational 

 ingredients in chemical union. When the lady would send him back 

 from love-making to astronomy, he contrives to give both together, 

 and, consistent to the close, takes leave of his charming scholar with 

 the modest request that, as sole reward for his pains in teaching her 

 the heavens, she will never again look on sun, moon, or stars, without 

 thinking of him. 



THE BALL-PARADOX. 



By THOMAS S. CRANE, Mechanical Engineeb. 



THE exhibitors of the atmospheric air-brake, at the Centennial, 

 attached a tube to the air-reservoir for the purpose of showing 

 the immense pressure employed. 



The current rushing from the small orifice of the tube sustains 

 balls of varying gravities, according to the pressure applied. 



Once, on accidentally resting the base from which the tube springs 

 upon something lying on the table, it was found that, although no 

 longer vertical, the current of air still held the ball in suspension, the 

 ball revolving rapidly, and apparently hanging to the jet of air, which 

 strikes the sphere at its upper side. 



Fig. 1. 



It also makes little difference in the result whether the ball be a 

 solid glass one an inch and a half in diameter, or a hollow rubber 

 ball, or a solid wooden one three or four inches in diameter, the only 

 variation being the distance at which the spherical body is held from 

 the orifice. 



"When a glass ball with interior colored lines, such as children 

 play with, is gently held in the current until the air has the sphere 

 well in its power, it will rotate partly back and forth at first, and, 



