A boy thirteen years old and weighing 156 pounds, his height being 6 feet, 1 inch (there are such cases), would have a basal metabolism of 2300 calories, or larger than that of any grown man given in the table--larger than a man weighing 211 pounds and 6 feet, 4 inches in height. I personally know a boy of this age and size. His parents are said to have sent him to boarding school in order to reduce their food bills. It is evident from this discussion that the food requirement of boys over twelve years old is about the same as that of men. The emaciation of the children of the poor probably reduces their requirement of food. It is not generally recognized that the boy needs as much food as his father. The requirements of girls have not been investigated, but they probably need as much as their mothers. These data will give with close scientific precision the _minimal requirement for energy_ which is necessary for the maintenance of the bed-ridden. Ordinary life, however, is not constituted after this fashion. "By the sweat of thy brow shalt thou eat bread." From the work of F. G. Benedict one may calculate the increase in the basal metabolism, as follows: Increase in the basal metabolism Occupation in per cent. Sitting 5 Standing, relaxed 10 Standing, hand on a staff 11 Standing, leaning on support 3 Standing, "attention" 14 If one wishes to determine from the basal metabolism table the heat production of a person who is confined to his room, one should add to the metabolism of the twenty-four hours the increase above the basal for those hours of the day during which he is sitting in a chair or standing. Passing to a consideration of the subject of mechanical work done by a man, one finds that it requires about 1.1 calories to transport a pound of body weight three miles during an hour, and that increasing power must be generated if the speed is increased above this rate of _maximal economic velocity_. These relations are shown below: Extra calories per hour required to move 1 pound Rate of movement of body Walking 3 miles per hour 1.1 Walking 5.3 miles per hour 3.6 Running 5.3 miles per hour 3.1 If one wishes to determine the heat production of a man weighing 156 pounds and 5 feet, 7 inches in height, and who is walking or running, the following calculations can be made: Rate of travel per hour in miles 3[3] 5.3[3] 5.3[4] Cals. Cals. Cals.