Browning's New Aneroid Barometer. 



41 



of the beam is fastened to the upper wall of the vacuum cham- 

 ber (v), and when the air tries to make the chamber collapse by 

 pressing upon it with a given force, the weight at the long 

 end of the beam is an exact counterpoise. If the air pressure 

 exceeds this quantity, the weight is raised to a proportionate 

 extent. If the air pressure is lessened, down goes the weight, 

 just as the weight attached to the steelyard goes down, if 

 after having balanced a leg of mutton we take off a slice. 



BROWNINGS NEW ANEBOID 



Of course the motions are very small, but they are magni- 

 fied by levers, as shown in the drawing, and cause an aluminium 

 pointer (p) to traverse a considerable arc. 



If it is desired to exhibit the minute oscillations of the 

 vacuum chamber's walls on a very large scale, it becomes 

 practically necessary that the hand which has to move over a 

 wide arc should be extremely light, and in addition to the 

 slender metallic pointer which will move over three or four 

 inches when the walls of the chamber have moved through 



