RESPIRATION. 123 



should be well extended, somewhat more than repre- 

 sented in the figure. Fix a sheet of paper to the table 

 under the recording pencil at a. To take a graphic 

 record of the contour of the thorax, proceed as follows: 



(18) (#) Let the observer place the tracing point b 

 upon the "starting point" in the distal side of 

 the thoracic perimeter. 



() Sweep the tracing point quickly around one- 

 half the perimeter to a point approximately oppo- 

 site to the starting point. 



(V) Rotate the curved arm of the instrument upon 

 its axis bx, through 180. 



(d?) Sweep the tracing point around the other one- 

 half of the perimeter to the starting point. 



(>) The movements of the tracing point, b, in the 

 horizontal plane have been faithfully recorded 

 upon the sheet of paper by the recording pencil 

 at a. It is hardly necessary to remind the student 

 that the subject must remain motionless during 

 the observation. 



(19) Take a thoracic perimeter with the chest in re- 

 pose. Measure different diameters of the tracing 

 and multiply by five to reduce to actual measure- 

 ments. 



(20) Take a tracing at end of forced expiration; at 

 end of forced inspiration. Compare diameters. 



(21) Make a series of these tracings for different in- 

 dividuals. Compare. 



(22) Formulate conclusions. 



