BEHAVIOR OF SOME SOIL INSECTS. 



163 



as readily as it enters and as a result static pressure is produced. 

 This pressure is indicated through opening () on the inclined 

 manometer. Further, since opening (C) is smaller than opening 

 (B) the air escapes through (C) into chamber (2) the same as if 

 into the free atmosphere or without exerting any static pressure. 

 If, however, the rubber tubing connecting opening (B) with the 



FIG. 2. Showing a diagrammatic section of the diaphragm chambers and gage. 

 For description see text page 161. The number of units in the scale is here reduced 

 to ii for convenience. The number in the gages in use is 17, each representing 

 one millimeter of water. 



experimental cage is long or crooked, static pressure may be 

 exerted in chamber (2) due to the friction of the air in the tubing, 

 or the tubing may become kinked or closed in which case the air 

 would pass out through opening (E) and the inclined manometer. 

 To remedy this possible chance of error it is advisable to have 

 chamber (2) connected with end (Y) of the manometer. If this 

 is done only the difference in static pressure between chambers 

 (i) and (2) is indicated or the actual amount of pressure exerted 

 by the air flowing through opening (C). By using diaphragms 

 with different-sized openings different volumes of air can be 



