THE TABLES: EXPLANATORY 



9 



of 1 per cent, carbolic acid, rinsed with water, and dried 

 before reinsertion into the tube. A fresh mouthpiece 

 should be used for each subject. The subject should be 

 seated on a high stool, with his back straight, opposite 

 the spirometer (Fig. 3), the dial being so placed that he 

 cannot see the readings. This is done for the purpose of 

 keeping him in ignorance 

 of the readings while being 

 examined, as it is found 

 that any such knowledge 

 lends to interfere with the 

 accuracy of the results. 

 The neck, chest and ab- 

 domen must be free from 

 any obstruction to free 

 movement, such as collar, 

 belt or stays. The subject 

 is asked to fill the lungs 

 to the maximum capacity, 

 then the nose is held with 

 one hand, the mouthpiece 

 is placed well inside the 

 lips with the other hand 

 in such a manner as to 

 prevent any escape of air 

 round it. He now blows 



steadily into the tube, and empties the lungs as 

 completely as possible into the spirometer, being en- 

 couraged during the last period of expiration to make 

 the utmost effort to expel all air from the lungs. The 

 readings are given in litres and decimals of litres, to be 

 read directly from the dial. After each expiration the 

 needle on the single-litre dial should be brought back to 



Fig. 3. Testing the vital capacity. 



