240 APPENDIX 



contour the cross-sectional area of the thorax in the plane of the 

 ninth rib is represented by 25.52 of the larger squares containing 

 25 square cm.; total area equals 637.5 square cm., while the cross- 

 sectional area of the chest in forced expiration is 517.5 square cm. 

 Forced inspiration shows an increase of 120 square cm., or about 

 23 per cent., over cross-sectional area of forced expiration. Further- 

 more, both contours show a prominence in the right side (left of the 

 figure), possibly due to stronger musculature on that side. 



17. THE PNEOMANOMETER. 



This instrument may be easily constructed in the laboratory. 

 Take a piece of heavy glass tubing 7 to 9 mm. lumen and at least 

 160 cm. in length. Bend it as shown in Fig. 61. A covered filter 

 may be attached as shown in the figure if there is any tendency for 

 the mercury to be thrown out. 



