92 ELEMENTARY BIOLOGY 



129. Respiration calorimeter. The work of the human body 

 or any other animal body can be measured in terms of calories 

 by means of very delicate apparatus that has been developed in 

 recent years. In a large chamber that is completely inclosed so 



FIG. 33. The respiration calorimeter 



In the large chamber a man can live for several days or weeks under conditions that give 

 an accurate account of his body's income and expenditure, in the way of matter as well 

 as in the way of energy. A, door and window ; B, door for food etc. ; C, tank for catching 

 water circulating through the walls of the chamber ; Z>, observer's table, with devices for 

 measuring and regulating temperature etc. ; J5, rubber bag to equalize the air pressure 

 within the chamber ; F, apparatus for circulation and purification of air in the chamber. 

 From photograph furnished by Office of Home Economics, United States Department 



of Agriculture 



as to prevent the escape of heat, a person may live for several 

 days or weeks at a time under conditions that allow us to measure 

 every particle of material that goes in or that comes out, as well 

 as the amount of heat that is given off by the body (Fig. 33). 

 With this apparatus exact records are made of the work a 

 human being does in the course of a day, measured physically 



