122 VITALITY AND EFFICIENCY WITH RESTRICTED DIET. 



it difficult to keep the apparatus clean. On the other hand, when the 

 skirt was once put in place in the oil seal a of the base, it was not 

 necessary to disturb it except to get at the lower part of the mill for 

 oiling or for attention to the motor. 



Fig. 14. — The treadmill chamber. 



The treadmill rests on the base A, which has an oil seal, a, into which the skirt B fits. The subject 

 stepped over the side of the skirt on to the treadmill and the cover, C, was lowered into the 

 water seal, h, of the skirt. The treadmill was driven by the motor D, controlled by resistances 

 not shown in the figure. Fans E and E' stirred the air and a blower, F, forced the air past the 

 psychrometer, G, through the drier H. From H, the pipe went through a partition, /, into 

 an adjoining room where samples of air were drawn at J for analysis. The air returned to 

 the chamber through L. which was removable at the water seals K and K'. M, the tension 

 equalizer or spirometer connected to a reserve spirometer M'. Ni, N2, N3, Ni, and Nb, 

 resistance thermometers in series; a sixth one is not shown in the figure. O, window; P, 

 electrical plug for temperature and pulse leads. Q, electrical plug for distance and step 

 counters. R, electrical contact for recording revolutions of front pulley. 



