242 CARNEGIE INSTITUTION OF WASHINGTON. 



The new calorimeter is the largest ever built for man and is 

 so constructed as to permit the measurement of the excessive 

 amounts of heat given off by a man doing severe muscular work. 

 The chamber is large enough for a man to stand upright in it and, 

 indeed, to walk upon an inclined treadmill. The treadmill designed 

 by Mr. Metcalf for use in this apparatus secures minimum friction and 

 regularity of motion. For experimental work it is placed inside the 

 respiration chamber and actuated by an electric motor. It is thus 

 possible to measure the total carbon-dioxide output, oxygen consump- 

 tion, caloric output, water vaporization, and the distance walked by 

 a man on the treadmill, as well as the height to which the body is 

 raised by the inclination of the treadmill. An extension in the top 

 of the chamber permits the introduction of an endless ladder running 

 over a large pulley, so that the subject can climb a ladder continuously, 

 thus raising his body almost perpendicularly and doing a very large 

 amount of work. By reversing the direction of the ladder and the 

 treadmill the interesting problem of negative work can be especially 

 well studied. 



ELECTRICAL RECORDER FOR HEAT MEASUREMENTS. 



The calorimeters in the Nutrition Laboratory are at present of the 

 so-called continuous-flow type, i. e., a current of cold water passing 

 through an absorption circuit permits the carrying away of the heat 

 as fast as it is developed. To determine the amount of heat given 

 off by the subject, it is necessary to take the temperature of the 

 water as it enters and leaves the chamber. In 24-hour experiments 

 and in severe-work experiments this requires considerable labor on 

 the part of the assistants, with possibility of error. An electrical 

 recording device, which will graphically record the temperature dif- 

 ferences of the water-current, has long been sought, and it was a 

 cause of much disappointment that the recording device described 

 in Pubhcation No. 123 did not function perfectly for a reasonable 

 length of time; but it is a pleasure to record the success of our 

 physicist, Mr. E. H. Lange, in reconstructing this defective apparatus 

 and making it practicable for experimental work. 



RESPIRATION APPARATUS. 



The form of respiration apparatus developed in this Laboratory, 

 which is applicable alike for experiments with men, infants, and 

 animals, has necessitated the construction of several other models, 

 and there are now seven of the universal respiration apparatus in 

 use in different parts of the Laboratory. Several modified forms 

 of the spirometer used in connection with this apparatus have been 

 built, one for permitting more accurate analysis of the curves corre- 

 sponding to the volume of each individual respiration, and another 



