1038 EXPERIMENT STATION RECORD. 



the fuiidanuMitul })liysiol()*;ical laws upon whit-li a rational practice 

 nuist necessarily he based. 



In 181KS, encouraged by the success which had attended the investi- 

 gations with the Atwater-Rosa respiration calorimeter at Wesleyan 

 University, the Pennsylvania Experiment Station and the Hureau of 

 Animal Industry of the U. S. Department of Agric-ulture undertook 

 in cooperation the construction and operation of a similar apparatus 

 for studying the fundamental principles of the nutrition of farm ani- 

 mals (Pis. IV and V). It was determined to make the apparatus 

 large enough for experiments with cattle, and in view of the costly 

 and unique nature of the apparatus the erection of a special building 

 for housing it was authorized by the trustees of the college. 



Work upon the apparatus was begun in the fall of 1898. In addi- 

 tion to the numerous problems of construction involved in the consid- 

 erable enlargement of the apparatus, other questions had to be solved. 

 Thus, no cooperation could be had from the subject of the experiment, 

 but everything relating to the conditions inside the apparatus must be 

 adjustable by the observer without. Moreover, for experiments with 

 cattle large amounts of bulky food and excreta had to be introduced 

 into or removed from the apparatus. A further complication arose 

 from the considerable production of combustible gases by ruminating 

 animals, rendering it necessary to provide special means for their 

 determination. As a result of all these difficulties, the construction 

 proved slower and more expensive than was anticipated, extending 

 over nearl}^ three and one-half 3^ears. Preliminary tests were com- 

 pleted and the first actual experimental work begun early in the year 

 1902. 



GENEKAI. PLAN. 



The general plan of the apparatus is substantially that of the Atwater- 

 Rosa apparatus; that is, it is a Pettenkofer respiration apparatus, the 

 chamber of which serves also as a calorimeter. The original Middle- 

 town apparatus has been fully described in bulletins 63 and 136 of the 

 Office of Experiment Stations, and the reader is referred to these pub- 

 lications for details on many points. 



The respiration chamber of the Penns3dvania apparatus (figs. 11 

 and 12) is constructed of sheet copper, and measures 6 feet by 10 feet 

 4 inches and S feet high. A platform 21 inches above the base of the 

 chamber carries the stall in which the animal stands. Beneath the 

 rear portion of this stall is a small chamber of sheet copper about 34 

 by 67 inches, entirely shut off' from the rest of the respiration chamber 

 except for two holes through the platform, and having a separate air- 

 tight door. Through one of the holes mentioned a rubber tube leads 

 from the urine funnel to a receptacle of tinned copper; to the other 

 hole is attached a large rubber duct covering the hind quarters of the 



