1903-4.] Prof. Schafer on Artificial Respiration in Man. 43 
in the prone position. The amount of pressure used in the last 
two methods was approximately the same, having been produced 
by throwing the whole weight of the fore part of the body of 
the operator upon his hands, which were placed over the lowest 
part of the thorax of the subject, the only difference being that 
in the one case (Howard) the subject was supine, in the other 
prone. The pressure was in every case applied and removed 
gradually ; a pressure of about 60 lbs. was thereby exerted. 
Fig. 5. — Prone pressure method. 
Pig. 6 shows two tracings obtained by permitting the subject 
to breathe, under approximately natural conditions, into the 
spirometer, and the steps on these tracings give, therefore, an 
idea of the amount of tidal air. The rate of respiration on this 
occasion was about 16 per minute, and the average amount of 
air exchanged at each respiration ( i.e . the amount of tidal air) 
was 385 c.c., or 6160 c.c. per minute. Before and after these 
two tracings, others were made with employment of the prone- 
pressure method; and these, which are also shown in the figure, 
illustrate well the efficiency of that method in providing a due 
exchange of air. 
