192 REPORTS ON INVESTIGATIONS AND PROJECTS. 



junctions any slight temperature differences between the inner copper wall 

 and an outer zinc wall are constantly noted. The temperature of the zinc 

 wall is arbitrarily adjusted by heating and cooling to maintain it at the tem- 

 perature of the copper wall, thus holding the calorimeter in an adiabatic 

 condition. The chambers are large enough for a man to remain comfortably 

 seated or lying for several hours, an electric light furnishes illumination, 

 connection is made by call-bell and telephone with the outside, and a supply 

 of air is continually circulated through the chamber and thence through 

 weighed vessels containing sulphuric acid and soda-lime to absorb quantita- 

 tively water-vapor and carbon-dioxide. The oxygen consumed is determined 

 by admitting the gas from a weighed cylinder of highly compressed pure 

 oxygen. Analyses of the air residual in the chamber are made at the end 

 of every period and corrections for barometric changes are applied. Elec- 

 trical resistance thermometers are used to measure calorimeter as well as 

 body temperatures. A stethoscope and pneumograph permit the measure- 

 ment of the pulse-rate and respiration-rate. A graphic record of the minor 

 muscular movements is also furnished by the tracing of the pneumograph 

 tambour. The apparatus has been most carefully checked as a calorimeter 

 by the development of the heat from a known electrical current inside the 

 chamber, and the accuracy of measurement of all four factors — carbon 

 dioxide, water-vapor, oxygen absorption, and heat production — has been 

 controlled by burning known weights of pure ethyl alcohol. The methods 

 of calculation and the details of the routine of an experiment with man are 

 included. The apparatus has proved highly successful for 6-hour to lo-hour 

 experiments with men and women, and experiments may be subdivided to 

 i-hour periods with accurate results. 



(7) The metabolism and energy transformations of healthy man during rest. Francis 

 G. Benedict and Thorne M. Carpenter. Publication No. 126, Carnegie Institu- 

 tion of Washington. 1910. 



In the decade during which the experiments were in progress with the 

 respiration calorimeter at Wesleyan University, Middletown, Connecticut, a 

 large amount of material on the normal metabolism of healthy men and 

 women was accumulated. This material has been in part published in other 

 reports, but much of it has never been published and is collected here for 

 final presentation. Among the subjects discussed in detail are the changes 

 in body-weight, the insensible perspiration, body-temperature with its varia- 

 tions and fluctuations, and pulse-rate. By means of the respiration appa- 

 ratus, important data with regard to the vaporization of water from the 

 body of the subject were accumulated, and these are discussed at some 

 length in connection with the elimination of carbon-dioxide, oxygen con- 

 sumption, and the heat elimination and heat production. Special reference 

 is made to comparisons between the metabolism during sleep and during 

 waking hours and the relationships between the different factors of metabo- 

 lism. The variations in metabolism due to variations in physical charac- 

 teristics, age, muscular activity, sex, etc., have received especial attention, 

 including the metabolism of athletes, non-athletes, and women. A number of 

 experiments dealing with the metabolism and energy transformations inci- 

 dental to simple every-day body movements are also included and tentative 

 tables for the computation of the metabolism of normal individuals with 

 varying degrees of muscular activity are given. 



