130 VITALITY AND EFFICIENCY WITH RESTRICTED DIET. 



the treadmill in the chamber or a second subject resting in an adjoining 

 room to be in circuit with the string galvanometer. In this way elec- 

 trocardiograms could be taken alternately from two subjects with but 



little loss of time. 



As a rule the pulse was recorded photographically for a period of 15 

 to 20 seconds, first while the subject was sitting in an adjoining room, 

 then while standing either in the adjoining room or on the treadmill 

 before the walking started, and again at the end of the first, sixth, 

 twelfth, and twenty-fourth minutes of walking. During the walking 

 periods of January 28 and February 3 a visual pulse count was also 

 made each minute by observing the deflections of the string for 15 to 20 

 seconds. A record of the pulse-rate was thus secured on these two 

 dates for each minute of walking, either by the photographic method or 

 by visual count with the aid of a stop watch. 



In the experiments of January 28 and February 3, electrocardiograms 

 were also secured of the pulse at the time of transition from standing to 

 walking at the start, and again from walking to standing at the close of 

 the period. As a rule these transition records consisted of 15 seconds 

 of the first stage and 60 and 30 seconds of the final stage of the transi- 

 tion. A reproduction of a typical group of records for one subject is 

 shown in figure 16. Finally the radial pulse was counted after the 

 walking had ceased and the subject had been sitting quietly for 4 

 and 8 minutes. 



For the records taken during sitting, standing, walking, and sitting 

 after walking, the counts were in terms of pulse-rate per minute. In 

 the transitional pulse records the individual pulse cycles were measured, 

 as was done with the electrocardiograms during short periods of exer- 

 tion described on page 151. 



RESPIRATION-RATE. 



A pneumograph worn by the subject around the lower chest was 

 connected to a tambour, shown at A in figure 17, by means of a 

 rubber tubing, B, which left the chamber by a brass tube in the rear of 

 the skirt-wall. On one radius of the diaphragm of the tambour was 

 cemented a light aluminum lever, C, the base of which pivoted on 

 the edge of the tambour which was segmented at this point.^ Sup- 

 ported by this lever a fine copper wire, D, dipped in a cup of mercury, 

 E. Each respiration, acting through the pneumograph and tambour, 

 made a contact between the wire and the mercury and operated a signal 

 magnet placed in front of the camera used for the electrocardiograms. 

 Adjustment of the contact in the mercury cup was made by means of 

 the reservoir, F, while a screw pinchcock, G, on the tube from the pneu- 

 mograph damped the movements of the l ever. The apparatus was so 



'A similar form of tambour making use of the principle of Frank's segmented capsule is 

 illustrated by Wiggers, Circulation in Health and Disease, Philadelphia, 1915. See 

 figure 11, page 57. 



