284 



RESPIRATION 



tory movemen- Adjust one of these, for example Burdon-Sanderson's 

 stethograph, to the thorax, and record the movement of the receiving tam- 

 bour on a smoked-paper kymograph which travels at the rate of i cm. per 

 second. This record, called a stethogram, will exhibit the respiratory rate, 

 the relative time of the inspiratory and expiratory phases, and the character 

 of each. 



3. The Actual Change of Diameter in the Chest in Respiration. 

 Use a caliper provided for the purpose and measure the dorso-ventral diam- 

 eter of the chest at a series of points along the sternum, taking the reading 



FIG. 242. Change in Diameter of the Body in Respiration, Costal Type, a, Outline of the 

 body in forced expiration. In the heavy continuous line, b, the outer margin indicates the contour of 

 the body in ordinary inspiration and the inner margin that of ordinary expiration, c, Contour 

 of forced inspiration. (After Hutchinson.) 



at the height of the inspiratory phase and of the expiratory phase in ordi- 

 nary respiration. Repeat the measurement in forced respiration. Map 

 the results on millimeter paper, as indicated in figure 242. 



Repeat these measurements in the transverse diameter at the first, fifth, 

 and tenth ribs. 



Using the chest pantograph, figure 243, record the outline of the chest 

 at the level of the middle of the sternum during expiration and at the end 

 of inspiration. 



4. The Volume of Air Breathed by Man. Determine the average 

 volume of air breathed per respiration, using Hutchinson 's spirometer, figure 

 235, set the instrument at the zero point, exhale into the instrument through 

 the tube, using all possible care to breathe with your normal rate and depth. 

 Better results will be obtained by taking the average from sets of ten consecu- 

 tive inspirations into the instrument. From the average of the volume per 



