378 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



stopper can glide freely along the rod when placed in the inverted 

 bottle."*. After inserting the glass tubes as shown in the illustration 

 (fig. 66), the wooden rod is inserted through the stopper from the side 

 that goes into the bottle ; then the smaller end of the rod is attached to 

 a block. The large bottle is suspended in an inverted position from one 

 end of the balance beam of the stand, the stopper is inserted, and the 

 small bottle, nearly filled with water, is hung on the opposite end of the 

 beam for counterpoise. The block carrying the wooden rod is moved 

 about on the base of the stand until the stopper moves easily up and 



Fig. 66. 



down the rod, and is then fastened in this position with a wood screw. 

 If the head of the rod fits the hole in the stopper accurately no water 

 will escape when it is turned on until the weight of water in the 

 inverted bottle exceeds that of the counterpoise ; the weight of the 

 counterpoise may be adjusted so that it will keep the large bottle about 

 one-third full of water, thus preventing the escape of air except through 

 the proper outlet. The water and air should not discharge alternately, 

 and if this take place a longitudinal groove may be cut into one side 

 of the head in the stopper until enough water escapes to balance the 

 inflow when the water pressure is at its lowest. From this point onward 

 it will work automatically. 



