514 



PHYSIOLOGY. 



that have been consumed. There are various types of calorimeters 

 in existence, but it has only been within the past few years that 

 results at all exact have been attained. 



The calorimeter employed by the author in his laboratory experi- 

 ments is constructed as follows : It is composed of two cylinders of 

 galvanized iron- one smaller than the other and inclosed within the 

 larger. The space in which the man lies upon a mattress is six feet 

 long and two feet in diameter. Air is conveyed to him through the 

 tube (H) which traverses the whole length of the apparatus to enter 

 the hollow tube of lead at F; it finally emerges at B, after having 

 given off its heat to the water between the two cylinders. The 

 meter (M) is run by the water-wheel (N), which aspirates the air 

 through the entire apparatus by means of a hose (R) connecting it 

 with the lead tube at B. 



Fig. 180. Human Calorimeter. 



The space between the cylinders is filled with about 484 pounds 

 of water. This water is kept thoroughly mixed by means of the agi- 

 tator (0), which has two arms. The arms are pushing the water 

 back and forth thirty times a minute, the motion being caused by the 

 electrical motor (X), whose wheel (3), with its eccentric, drives the. 

 agitator. The thermometer (A) gives the temperature of the water; 

 because of the thorough mixing of the water by the agitator it gives 

 an accurate record of the temperature of the water throughout the 

 apparatus. The thermometer is pushed down farther than is repre- 

 sented in the illustration. It usually lies aside of the tube(//). The 

 air-tube (B) also has a thermometer to denote the temperature of 

 the air as it is heated by the man. The thermometer at B is grad- 

 uated into tenths, while that at A is graduated into fiftieths. The 

 markings are so far apart that one one-hundredth of a degree Fah- 

 renheit can be read. 



