M. Carey Lea on a Constant Aspirator and Blower. 247 



rubber tube with a straight tabe of equal diameter. This last 

 arrangement forms the siphon. 



When the apparatus is to drive a blast, an india-rubber tube 

 is connected with a hydrant and attached to the open end of the 

 short horizontal branch of the tin tube. When the water is 

 turned on, the india-rubber tube, G I, is closed for a moment 

 with the finger and thumb. This starts the water through the 

 siphon, and then a continuous and powerful blast of air is 

 driven through the tube, GI, which may be attached to a blow- 

 pipe, a Herapath burner, or be used in any way desired. The 

 main point is this, that the siphon must be capable of carrying 

 off a larger stream of water than that which is allowed to enter: 

 in this way there is never more than an inch or two of water in 

 the bottle, and some air escapes through the siphon, but without 

 stopping its play. Otherwise the bottle may fill up and water 

 be driven through G I. The proper balancing is easily attained 

 and then the apparatus may be put in motion or stopped in a 

 moment, and when in motion goes on indefinitely. 



When the apparatus is to be used as an aspirator, the tube I 

 IS closed by inserting a glass rod, or passing over it a Mohr's 

 stop-cock. B is closed by a cork and E is connected with the 

 apparatus through which the c - -^ • • . i i t^ 



[• than A 



When the water is thrown horizontally i 

 appears to carry with it a larger volume 

 diiced perpendicularly or in an inclined position. Although the 

 force of the current of air may be regulated to a considerable 

 extent by diminishing or increasing the stream of water, yet it 

 IS to be observed that there must be a certain proportion be- 

 tween the stream of water and the size of the tube ; a large tube 

 ceases almost abruptly to produce any air-current when the 

 stream of water is reduced below a certain point, and a small 

 tube will not give an air-current of more than a certain force, no 

 flatter how great the stream of water. If it is desired that a 

 f.'fgle apparatus shall produce all degrees of action, a tin tube, 

 [ike that before described but a little larger in all its parts, may 

 t)e provided, with a cork fitting its upper extremity. Through 

 a bole in this cork passes a thick glass rod, or tube sealed at one 

 «nd, of the same length as the tin tube. The introduction of 

 tbis cork and rod diminishes the effective calibre of the tube, 

 and enables it to blow or aspirate a gentle current of air with a 

 stream of water which would otherwise have failed to set the 

 apparatus in motion; at the same time it can easdv be removed 

 when a powerful air-current is desired. The air in this case is 

 derived wholly from the small inclined tube. 



