8 



THE TABLES: EXPLANATORY 



THE VITAL CAPACITY. The term "vital capacity" 

 is used to indicate the maximum amount of air an indi- 

 vidual is able to expel from the lungs by voluntary 

 effort, after taking the deepest possible inspiration. In 

 measuring the vital capacity it is essential to use an 

 apparatus that affords the least possible resistance to 



FIG. 2. Spirometer. 



expiration, and at the same time gives easy and accurate 

 readings of the amount of air expired. The most suitable 

 apparatus has been found to be a spirometer made by 

 Georges Boullite of Paris (Fig. 2). 



Naturally, however, any accurate apparatus having 

 the same advantages can be used. A flexible tube of 

 sufficiently large diameter (about 2 cm. or f in.) should 

 be attached to the apparatus. In the free end of the tube 



