152 BENEDICT— THE INFLUENCE OF [February 4, 



concerned is pretty well fixed and it is also true that man at very- 

 severe muscular exercise means practically the limit of human en- 

 durance. 



Using the values in this table it is possible to roughly compute 

 the average daily output of heat from a man at light muscular 

 work or the heat from a man with different degrees of muscular 

 work. Assuming, for example, that the man is at light muscular 

 work, the computation is as follows as given in Table II herewith. 



TABLE II. 

 Average Daily Output of Heat of a Man at Light Muscular Work. 



Daily Program. Heat Output. 



At rest, sleeping, 8 hours, 65 calories per hour 520 



At rest, awake, sitting up, 6 hours, 100 cal. per hour 600 



Light muscular exercise, 10 hours, 170 cal. per hour 1,700 



Total output of heat, 24 hours 2,820 



The computation of the average daily output of heat on this basis 

 is at best somewhat unsatisfactory, as we do not know with suffi- 

 cient accuracy the heat output during the various degrees of mus- 

 cular activity. Nevertheless, it serves to give a general idea of the 

 possibilities of using standard normal values for getting a rough 

 approximation of the energy output of different men with different 

 conditions of muscular activity. 



We are all of us firmly of the opinion that when we are doing 

 strenuous mental work, we are doing a great deal of work. We 

 feel sometimes perfectly exhausted at the end of a severe mental 

 task, and consequently it will be interesting to note to what degree 

 mental work influences the interchange of material in the body. 

 Does severe mental application call for a greater production of 

 heat or a greater oxidation of the tissues? In order to test this 

 question satisfactorily, it became necessary for us first to try to find 

 out how to get men to work hard mentally for a period of several 

 hours. 



While at Wesleyan University, it occurred to me that it might 

 be desirable for us to study the metabolism of students during the 

 mid-year examination period, for if there is any time in which a 

 college student performs mental work, it is during the examina- 

 tion period. Consequently it was arranged for students to take 



