112 



SPECIAL PH YSIOL OG? 



(a) Let the observer place the tracing point (t) upon the "starting 

 point" on the distal side of the thoracic perimeter. 



(b) Sweep the tracing point quickly around one-half the perimeter 

 to a point approximately opposite to the starting point, 



(c) Rotate the curved arm of the instrument upon its axis (t x) 

 through 180 degrees. . 



FIG. 60 



FIG. 61 



FIG. 60. The water spirometer. The outer receptacle contains water. The inner inverted 

 reservoir receives the air through the mouth tube, at the right, and is raised. 

 FIG. 61. Pneomanometer. 



(d) Sweep the tracing point around x the other one-half of the 

 perimeter to the starting point. 



The movements of the tracing point (t) in the horizontal plane have 

 been faithfully recorded upon the sheet of paper by the recording 

 pencil at r. It is hardly necessary to remind the student that the 

 subject must remain motionless during the observation. 



