80 VITALITY AND EFFICIENCY WITH RESTRICTED DIET. 



tested in a series of observations with a group of approximately 25 

 individuals several months before. 



RESPIRATORY-VALVE METHOD. 



For the most reliable measurements of the basal gaseous metabolism 

 we took advantage of the newest technique developed in the Labora- 

 tory. This included the use of a special form of mask, Thiry-Tissot 

 valves, a spirometer, and the Haldane gas-analysis apparatus. By 

 means of two spirometers it was possible to obtain the gaseous metab- 

 olism in at least two periods each on two men every morning, thus 

 securing observations on each member of the squad at least once a week. 

 In the last few weeks of the research, the routine was so altered that 

 measurements were obtained with this procedure on three men each 

 morning. While the various sections of the apparatus have been ex- 

 tensively described by Dr. T. M. Carpenter of the Nutrition Lab- 

 oratory staff,^ the exact combination of appliances used (due, as a 

 matter of fact, to the technical skill of Dr. Carpenter) has not been 

 described in extenso and a few words are here desirable. 



Believing that for the most accurate measurement of the respiratory 

 exchange and especially the respiratory quotient, untranmaeled respi- 

 ration is desirable, Dr. Carpenter has used a face mask provided with 

 inlet and outlet valves which communicate, in turn, with a pipe leading 

 to the outdoor air and another pipe leading to a Tissot or similar type 

 of spirometer. By means of a small canvas cap and suitable straps, 

 this mask can be so firmly attached to the face as to make it air-tight. 

 With reasonable care in application, the mask will be sufficiently com- 

 fortable for the subject to wear it for a half hour or more; occasionally 

 the subjects fall asleep — a proof of absence of discomfort. 



As used in the daily observations with Squad A, the mask was 

 first attached and the valves examined to find if they were working 

 smoothly. The expired air was then allowed to pass into the room for 

 several moments, but at a given time connection was made with the 

 spirometer and the air expired by the subject was collected in the 

 spirometer for a period of approximately 10 minutes. To provide exact 

 information as to the degree of repose of the subject, as well as graphic 

 records of the respiration, two pneumographs were placed one about 

 the chest and the other about the thighs; these were connected with 

 suitable tambours which recorded upon the smoked surface of a kymo- 

 graph drum. By this method the activity was instantly recorded, also 

 each respiration. By means of the respiration record, the character as 

 well as the rapidity of the respiration could be seen. Finally, the 

 importance of knowing whether the subject was asleep or awake during 

 the observations led us to obtain by means of a signal magnet writing 

 upon a kymograph drum records of the responses to a stimulus given 



^ Carpenter, Carnegie Inst. Wash. Pub. No. 216, 1915, p. 61. 



