380 CORRECTION TO BAROMETER FOR FORCE OF WIND. 
cock which confines the compressed air is turned, the air rushes out by the larger 
tube, drawing with it part of the air which was in the two boxes, and causing a 
partial vacuum—as is demonstrated by the fall of the barometers in each box. 
Sir Joun Lestie’s experiment is of a more simple nature, and will be under- 
stood at once by reference to the wood-cut. 
Fig. 3. 










































By blowing through a cylinder, to the lower sides of which a glass syphon, 
partially filled with water, is attached, he found that if the eduction-pipe was 
larger than the ene through which he blew, that a partial vacuum was formed in 
the cylinder, as indicated by the rise of the water in the leg of the syphon 
attached to it; but by reversing the instrument and blowing through the larger 
tube, he found that the air was compressed in the cylinder, and caused a depres- 
sion in that leg of the syphon. 
In the experiments of BrrnoviLui and Venturt, the rush of a stream of water 
through a horizontal tube made wide at the end by which the water escapes, is 
shewn to have the effect of drawing up water through a smaller pipe leading 
into it. 7 
In fig. 4. it is shewn that the water is drawn up and carried away by the rush 












































