OF DENISON UNIVERSITY. 
15 
ceiver now rests on the bottom of the water jar and enough water re- 
mains in the water jar to protect the open end of the receiver and ex- 
clude the air. 
To get the vital capacity, fill the lungs with the largest possible 
inspiration, place the tube to the mouth, open the clamp and empty 
the contents of the lungs into the receiver, at the end of the greatest 
possible expiration, close the clamp, read off the volume of air in the 
receiver, from the scale. 
When the first air is sent into the receiver from highly inflated 
lungs it is under some pressure which is about balanced by the weight 
of the water in the receiver, but when the water in the two vessels is 
at the same level, if more air is sent into the receiver it finds little or 
no resistence, as the weight then begins to act to support the weight 
of the receiver. 
To determine the three factors of the vital capacity of the lungs, 
the experimenter should be seated and should time his regular respira- 
tory movements and should use the receiver about half full of water 
in order to obviate suction or resistance as much as possible. 
It was found by the use of this instrument that the vital ca- 
pacity of the class was a little above the average and that by blowing 
the vital capacity regularly twice every day those students whose vital 
capacity was far below the average at the start, could be brought up 
to above the average in the course of two or three weeks. It is rec- 
ommended as a simple, cheap, and convenient lung strengthener. 
