BENEDICT APPARATUS, INCREASED DEAD SPACE. 207 



pneumograph fastened about the hips. The subjects were all members 

 of the Laboratory force and, with the exception of W. F. O'H., were 

 more or less trained subjects. 



The statistics of the 13 experiments are given in the following 

 pages. All of these experiments were made by Mr. P. F. Jones, whose 

 assistance in this portion of the investigation I wish to acknowledge. 



STATISTICS OF EXPERIMENTS WITH AN INCREASE IN DEAD SPACE OF 45 C.C. 



J. K. M., September 20, 1912. Without dead space, 3 periods; with dead 

 space, 3 periods; first, second, and fourth periods without dead space, remain- 

 ing periods with dead space. New form of glass nosepieces used (see page 62). 

 Subject noted no difference between the periods, so far as ease of respiration 

 was concerned, but did not like the glass nosepieces. Pulse-rate fairly regular. 

 Respiration for the most part regular; slightly more regular in the periods 

 with increased dead-air space than in those without. Sections of records 

 obtained with each condition of experimenting are given in figures 57 and 58. 

 Average barometric pressure, 758.9 mm.; average temperature of air in appa- 

 ratus, 22.6 C. 



FIG. 57. FIQ. 58. 



FIG. 57. Type of respiration of subject J. K. M. without additional dead space on 



September 20, 1912. Original size. 

 FIG. 58. Type of respiration of subject J. K. M. with 45 c.c. additional dead space on 



September 20, 1912. Original size. 



J. B. T., September 23, 1912. Without dead space, 4 periods; with dead 

 space, 3 periods; first two periods without dead space, thereafter alternating. 

 Subject reasonably quiet throughout experiment; increase in dead space did 

 not seem to cause him any perceptible difficulty. Pulse-rate regular except in 

 third and fourth periods without dead space. Respiration regular in rate and 

 character in all of the periods. Average barometric pressure, 766.3 mm.; 

 average temperature of air in apparatus, 19.0 C. 



W. F. O'H., October 27, 1912. Without dead space, 4 periods; with dead 

 space, 3 periods; first two periods without dead space, thereafter alternating. 

 Bandage used over subject's eyes. Subject stated that bandage made him 

 somewhat more sleepy; when additional dead space was used he found it 

 easier to breathe; with normal dead space he could inhale more easily, but there 

 was some resistance in exhaling; he also stated that the vibration caused by the 

 motor was less noticeable when the dead space was increased. Pulse-rate 

 fairly regular in the individual periods. Respiration-rate in early part of 

 experiment fairly regular, but in last three periods was irregular on account of 

 subject's drowsiness; there were many periods of apnoea, and it was necessary 

 for the observer to keep the subject awake. Sections of the records of respi- 

 ration are given in figures 59 to 62. The experiment was not particularly 

 successful, owing to the wide variations in the degree of wakefulness of the 

 subject. Average barometric pressure, 759.1 mm.; average temperature of 

 air in apparatus, 20.0 C. 



