38 



COMPARISONS OF RESPIRATORY EXCHANGE. 



The bell, c, of the spirometer is sus- 

 pended in an annular bath between 

 two metal cylinders, a and b. The air 

 enters at m and leaves at o. A wheel, 

 c , supported by an upright, /, carries a 

 cord, d, to the ends of which are at- 

 tached a rod connected with the bell 

 of the spirometer and a guide rod, 

 g, g, g. Part of the weight of the bell 

 is counterpoised by the weight, I, car- 

 ried by the string, t. On the rod, g, is 

 fastened a pointer, h, which writes 

 upon a cylinder the character of the 

 respiration. The clamp, s, supports a 

 wheel, r, which is moved by the fric- 

 tion of the string, /, 

 against r. A pawl, u, pre- 

 vents backward move- 

 ment. The point, w, 

 upon the periphery of 

 the wheel, r, touches a 

 spring at each revolution 

 and closes an electric cir- 

 cuit in which is placed a 

 signal magnet. 



FIG. 13. Details of spirometer, with recording attachments. 



