For very delicate work, a smaller unit is used, sometimes called the 

 "small calorie" and spelled by the engineers with a small c; this is the 

 gram-degree calorie, and is of course only one thousandth of a Calorie. 

 We measure fuel or energy value of foods in the "large Calories"; but in 

 ordinary reports and tables people do not generally make a point of spell- 

 ing Calorie always with a capital. 



Measuring the Body's Work^ For finding out how much energy an 

 organism actually transforms in a given time, the respiration calorimeter 

 was developed about the beginning of the century. Later types of calorim- 

 eter are all based on the general fact, established by experiment, that the 

 amount of energy set free by an organism is in direct proportion to the 

 amount of carbon it oxidizes. Accordingly, if we knew the exact amount of 

 carbon dioxide that a person breathed out in one day, for example, we 

 should be able to calculate the total amount of work he had done. But the 

 calorimeter measures this "work" as a physical fact — that is, as calories or 

 as foot-pounds — not as useful products, words written, nails driven, or 

 buttons sewed. 



The calorimeter has been of tremendous help in solving many problems 

 of nutrition, as well as problems of metabolism, under various exceptional 

 conditions, including illness. For example, it has been indispensable in de- 

 veloping high-altitude and stratosphere flying, in which the fliers are sup- 

 plied with oxygen in measured quantities. As the calorimeter becomes more 

 widely used in hospitals, in mining, and in industry, simpler types are de- 

 veloped, and simpler procedures too. Thus, we can determine the amount 

 of heat a person generates by measuring the amount of oxygen he consumes 

 — for under controlled conditions the body liberates 0.004825 Calorie for 

 each cubic centimeter of pure oxygen (see illustration opposite). 



Basal Metabolism It is extremely difficult to measure a person's con- 

 stant, or basic, metabolism during sleep. Investigators and medical men 

 have therefore agreed upon an arbitrary measure which is called basal 

 metabolism. This is the rate of energy expenditure by a person who is 

 awake, lying still and relaxed, and who has not eaten any food during the 

 preceding twelve hours. It is customary to take these tests early in the 

 morning before the patient has had any breakfast. This is the nearest ap- 

 proximation to basic metabolism that can be obtained with any device 

 other than the respiration calorimeter, of which there are but a few in the 

 country. 



Standards for Boys and Girls" The basal metabolism measurement has 

 been made with calorimeters on thousands of boys and girls. For com- 

 parison, the results are calculated to show the daily need "per pound of 

 body weight" (sec table, p. 121). Since these figures represent averages, 

 iSee No. 1, p. 135. -See No. 2, p. 135. 



118 



