BED CALORIMETER AND TENSION-EQUALIZER UNIT. 85 



absorbed per minute in cubic centimeters, the respiratory quotient 

 calculated to the nearest 0.005, 1 and the average pulse-rate calculated 

 usually to the nearest 0.5 beat per minute. The average number of 

 respirations per minute is also given; if the latter is obtained by 

 counting only three times during a period, this is given to the nearest 

 whole number; with a graphic record it is given to 0.1 respiration per 

 minute. In certain comparisons the total ventilation of the lungs per 

 minute, reduced to C. and 760 mm. pressure, the volume per respira- 

 tion calculated to 37 C. moist and prevailing pressure, and the com- 

 position of the expired air are also included in the tables. The experi- 

 mental data are arranged in all cases in chronological order by subjects. 

 The detailed results are followed by a summary and discussion. 



BED RESPIRATION CALORIMETER AND BENEDICT RESPIRATION APPARATUS 

 (TENSION-EQUALIZER UNIT). 



The development of the bed respiration calorimeter 2 and the Bene- 

 dict universal respiration apparatus (tension-equalizer unit 3 ) was car- 

 ried on simultaneously and extended over several years. During this 

 time many opportunities were given for comparative respiration experi- 

 ments. In these comparisons the periods with each apparatus were 

 generally in series, the apparatus first used varying. Occasionally 

 the experiment consisted of alternating series of periods with the two 

 apparatus. Usually the bed calorimeter and respiration apparatus 

 were in the same room, and as, in this comparison, the mattress was 

 placed upon a framework or metal plate, the subject could be readily 

 transferred from one apparatus to the other without muscular activity 

 on his part. As it was necessary to delay the beginning of an experi- 

 ment with the calorimeter until temperature equilibrium had been 

 obtained, the time intervening between the series with the two appara- 

 tus varied in length according to which apparatus was first used. 

 When changing from the respiration apparatus to the bed calorimeter, 

 a considerable intermission never more than one hour was required 

 before experimenting could again begin, while in changing from the 

 bed calorimeter to the respiration apparatus, the succeeding period 

 could usually be begun in about 15 minutes. 



The pulse-rate was measured by means of the Bowles stethoscope, 

 except that in a number of the calorimeter experiments the records 

 were made by the subject himself. With the stethoscope the pulse- 

 rate was counted by the observer as frequently as once in 5 minutes in 

 the calorimeter periods and as frequently as every 2 or 3 minutes in the 

 periods with the tension-equalizer unit. 



The respiration-rate was counted from observation by an assistant 

 or a graphic record was obtained with the chest pneumograph. The 



1 The average respiratory quotient is calculated from the average carbon dioxide and the 

 average oxygen figures. 



2 See p. 14. 3 See p. 21. 



