34 



ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING. 



sweep out completely the carbon dioxide in the system. When the 

 motor is stopped sufficient oxygen is admitted to bring the tension to 

 the original point; the volume of air in the system is then exactly the 

 same as at the beginning. The carbon-dioxide absorbers and the accom- 

 panying Williams bottle are weighed and a reading taken of the amount 

 of oxygen which has passed through the gas-meter, the data being used 

 subsequently for computing the carbon dioxide produced and the 

 oxygen consumed during the experimental period. 



MANOMETER BaOH, MOISTEN ER 



H a S0 4 H 2 S0 4 TRAP METER 



FIG. 2. Schematic outline of universal respiration apparatus. 



The general course of the ventilating current is shown by arrows. P, mouthpiece; N, 3-way 

 valve connecting subject with ventilating current; V 1 and V 2 , 2- way valves for carbon- 

 dioxide absorbing system; M, valve connecting with supplementary pipe E for eliminating 

 the dead-air space; S, petcock connection for tambour and kymograph for recording the 

 respiration. 



TREADMILL. 



In many of the earlier investigations for measuring the carbon- 

 dioxide output and oxygen consumption of a walking man, the subject 

 has been obliged to carry a respiration apparatus upon his back or 

 drag behind him a long tube attached to the breathing appliance. 

 In other studies the apparatus has been pushed along behind the 

 subject by an assistant. Obviously none of these methods are suitable 

 for experiments in which there is rapid movement. Furthermore, 

 while we have no desire to minimize the value of the Zuntz apparatus 

 an apparatus which has contributed largely to our knowledge of the 

 physiology of man, particularly for high altitudes it should be said 

 that the transportation of an unwieldy gas-meter and accessory appa- 

 ratus by a subject is open to serious objection. It has been shown 



