XXI. a. The flow of liquids through tubes, under the 



influence of intermittent pressure. 



b. The impulse wave. 



a. The influence of intermittent pressure. 



7. Appliances. Two glass tubes of about 6 mm. lumen and 

 about 75 mm. long; a thin elastic tube thin walled 

 black rubber of about the same lumen as the glass tube 

 and about 150 cm. long; a double valved strong rubber 

 bulb (about 7.5 cm. long); elastic tubing, large size; 

 very thick walled rubber tubing for joining up the appa- 

 ratus; Y tube; two flasks, or water receptacles; heavy 

 linen thread; a wide capillary and a -fine capillary or 

 a piece of glass tubing 10 cm. long for constructing the 

 same; 500 c. c. graduated cylinder. 



2. Preparation. Join the large elastic tube to the entrance 

 valve of the bulb. Couple the two glass tubes closely 

 and join one end to the exit valve of the bulb. Make 

 all joints as close as possible and tie tightly with thread. 

 Draw a coarse and a fine capillary tube from the 10 cm. 

 piece of glass tubing. 



j. Operation. Clasp the bulb in the hand and make rhyth 

 matical contractions at the rate of about fifteen in ten 

 seconds. The process will, of course, pump the water 

 from one flask into the other. 



4. Observations. 



a. Intermittent force and inelastic tubes. 



(1) Does the stream of water which is ejected from 

 the exit tube flow in a constant or in an intermit- 

 tent jet? 



