i86 



POPULAR SCIENCE MONTHLY. 



experiments, and by the combustion of 

 alcohol in a specially devised lamp. 



As indicating the character of the 

 work carried on by Professor Atwater 

 with this apparatus, a recent experi- 

 ment may be cited. In this the sub- 

 ject remained in the respiration cham- 

 ber for thirteen consecutive days, ma- 

 king the experiment the longest one on 

 record and in many respects the most 



method and facilities for studying the 

 fundamental principles of animal nu- 

 trition. This has been accomplished 

 by Dr. H. P. Armsby and J. A. Fries, 

 who, working in cooperation with the 

 Bureau of Animal Industry of the De- 

 partment of Agriculture, have con- 

 structed an apparatus of this type at 

 the Pennsylvania Experiment Station. 

 In adapting the apparatus to experi- 



Armsby-Fries Respiration Calorimeter. 



complete. There were three days of 

 work on a so-called sugar diet, three 

 days on a fat diet, one day of hard 

 work on a fat diet, two days of fasting, 

 and four days on a light and very 

 simple diet, the subject sleeping or 

 lying down during one day, sitting 

 up one day, and two days doing light 

 work on a bicycle provided with an 

 ergometer for measuring the work. 

 The observations were unusually com- 

 plete, including in addition to the 

 carbon, hydrogen and heat, the oxygen 

 and the income and outgo of sulphur 

 and phosphorus. A record of the body 

 weight was also made by a new method 

 in which the subject was weighed from 

 the outside. 



The adaptation of the respiration 

 calorimeter to use with farm animala 

 marks ;i decided advancement in the 



ments with large animals, it was neces- 

 sary not only to increase the size of the 

 respiration chamber, but to introduce 

 a considerable number of special fea- 

 tures so that the operations of feeding, 

 weighing, collecting the excreta, etc., 

 could be performed entirely from with- 

 out. Among the most interesting of 

 these are the devices for weighing the 

 heat absorbers from the outside, the 

 air lock for introducing feed and water 

 without allowing the escape of air from 

 the respiration chamber, and similar 

 devices for the collection of the liquid 

 and solid excretory products. 



By check experiments the apparatus 

 has been found to be very accurate, 

 the measured heat being practically 

 identical with the theoretical amount 

 produced by burning alcohol in the 

 respiration chamber. In ordinary 



