220 PNEUMATICS. 



phon, and after a while fills it, causing the stream to 

 cease running ; but syphons for this purpose, when only 

 a few rods in length, with several feet descent, are 

 usually found to succeed well. If the discharging 

 orifice is several times smaller than the tube, it is fre- 

 quently of material use, by causing a slow and steady 

 current through the syphon. 



