32 



ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING. 



carbon-dioxide absorbing systems. Each series of absorbers include 

 two bottles filled with moist soda lime for absorbing the carbon dioxide, 

 and also a small Williams bottle, containing sulphuric acid to absorb 

 the moisture given up to the dry air by the soda lime. The air, which 

 is at this point free from carbon dioxide and water, passes through the 

 2-way valve V z , and after being moistened in a small Williams bottle 

 to a comfortable degree for respiration, it continues until it passes 



FIG. 1. General view of apparatus used for walking experiments, with subject in position. 

 A, absorption apparatus; B, treadmill; C and D, oxygen supply; E, step counter and 



accessory apparatus. 



by the opening of the tube connected with the mouthpiece P and into 

 the tension equalizer. This tension equalizer is a large copper can, 

 over the top of which is fitted a rubber bathing-cap. From this copper 

 can the air finally returns to the intake side of the blower, oxygen being 

 admitted as required from a cylinder of the gas. Thus we have a com- 

 plete closed-circuit system, with the rubber bathing-cap acting as a 

 tension equalizer to compensate for changes in the volume of air as the 

 subject breathes in and out. 



