1910.] WORK ON NUTRITIVE PROCESSES. 157 



measured directly and also the amount of work in terms of calories 

 put on to the bicycle accurately determined by noticing the number 

 of revolutions of the pedals. We thus have a determination of 

 the total heat production and the heat of mechanical work which we 

 can compare with the total heat production and thus find the effi- 

 ciency. The degree of resistance of the electric brake varied from 

 mere coasting when no resistance is applied but the legs were made 

 to rotate as in coasting down a hill without a coaster brake, to such 

 a high resistance that the wheel would hardly be carried by the dead 

 point. The subjects used for these experiments varied. Two of 

 them, coming out of the wild woods of Maine, had never seen a 

 bicycle. Others were college athletes and were on the college 

 track team, and finally one of the most interesting experiments 

 was made with one of America's professional bicyclists. Air. Nat 

 Butler of Cambridge. 



In Table I\ , I have summarized a number of experiments with 

 these different subjects. 



TABLE IV. 



Experiments on Bicycle Riders. 

 (Calories per Hour.) 



Efficiency, 

 Resting. Working. ^ Work Done. Per Cent. 



J. C. W 112 339 49 21.6 



B. F. D io6 318 45 21.2 



A. L. L 105 2)^6 46 20.8 



E. F. S 117 399 51 18.1 



N. B 92 619 112 21.3 



471 79 20.8 



401 6s 21.0 



382 60 20.7 



In the first column under the title " resting " is recorded the 

 number of calories produced per hour by these difi^erent men when 

 sitting quietly reading in the respiration calorimeter. These experi- 

 ments are almost identical in their nature with the control experi- 

 ments in the mental work experiments and are intended to show 

 the heat requirement for maintenance during rest. These men 

 gave off, as you see, not far from 100 calories per hour, which 

 again is about the heat production of a 32 c.p. lamp. As they were 



" Including heat produced by the ergometer. 



