TECHNIQUE FOR METABOLISM DURING WORK. 



131 



designed that if desired a second subject might be alternately connected 

 to the tambour by means of a second tube, H, and the 3-way cock, /. 



When the subject entered the treadmill chamber the pneumograph 

 was connected to the tube in the rear of the skirt-wall and the proper 

 adjustment of the reservoir made so that the hair wire opened and 

 closed the circuit with each respiration. This actuated the signal mag- 

 net in front of the camera of the string galvanometer so that each time 

 the pulse was photographed a record of the respiration was also secured 

 on the same photographic film. A t3^ical section of such a record is 

 given in figure 16, in which the time in two seconds and fifths of a sec- 

 ond, the pulse, respirations, and steps are shown. 



The subject on the treadmill 

 wore a pneumograph which 

 was connected to a segmented 

 tambour A by means of 

 the rubber tubing B\ with 

 each respiration the tambour 

 caused the aluminum lever 

 C to complete an electric 

 circuit through the fine wire 

 D and the cup of mercury 

 E. This circuit operated a 

 signal magnet not shown in 

 the figure. F, mercury reser- 

 voir for adjusting the level 

 of the mercury in the cup E; 

 G, pinchcock for damping 

 the movement of the tam- 

 bour; H, a duplicate of B 

 for use with a second sub- 

 ject; I, 3-way stopcock for 

 throwing either B or H into 

 connection with the tambour. 



Fig. 17. — Respiration recorder. 



BLOOD PRESSURE FOLLOWING WALKING. 



Determination of the blood pressure by any of the various sphyg- 

 momanometers is exceedingly difficult during walking, since the sway 

 of the body, jar of the step, etc., all tend to make the readings uncer- 

 tain. Moreover, in these walking experiments the fact that the subject 

 was in a closed chamber precluded any thought of such an attempt 

 during the actual period. The only determinations feasible under these 

 conditions were records of the blood pressure shortly before and inome- 

 diately after walking, the latter continuing several minutes to note any 

 changes in pressure as the stimulus from walking decreased. 



The pressure was therefore taken with a Tycos sphygmomanometer 

 immediately at the close of the standing metabolism experiment. 

 The subject wore the cuff in place on his arm during the time he was 

 walking in the chamber. At the close of the walking period the 

 chamber cover was lifted, and while the subject was still walking the 

 cuff was inflated. The treadmill was then stopped. The systolic and 



