CALIBRATION TESTS 



17 



Table 3. Results of later calibration tests of ergometer I. 



[Experiments made in the chair calorimeter at the Nutrition Laboratory, Boston, Massachusetts.] 



The results of all of the later tests of ergometer I, made with the chair 

 calorimeter at the Nutrition Laboratory, Boston, Massachusetts, are 

 given in table 3, the averages alone being recorded. Special attention 

 is again directed to the column indicating the number of revolutions of 

 the pedals per minute and the heat per revolution. While it will be 

 remembered that in the earlier tests the rate of revolution of the pedals 

 varied only between narrow limits, i.e., from 70 to 90, here we find values 

 as low as 37 revolutions per minute and as high as 153. 



While no bicyclist could be expected to ride at the enormous speed of 

 153 revolutions of the pedals per minute, it may be interesting to note 

 that a professional bicycle rider, who has been recently experimented upon 

 in this laboratory, has repeatedly maintained speeds of 130 to 140 revolu- 

 tions per minute for 2 minutes at a time during a spurt; in fact, in ex- 

 periments with men, much difficulty has been experienced in securing a 

 low rate of speed. The tests with abnormal rates of speed are, however, 

 included more for the purpose of studying the peculiar relationship re- 

 cently noted between the revolutions per minute and the heat produced 

 per revolution. An examination of the results in table 3 again shows that, 

 in general, as would be expected, the greater the heat produced by the 

 magnetizing current the greater the heat per revolution. 



For an adequate study of the relationship between the number of revo- 

 lutions per minute and the heat per revolution, it was advisable to ex- 

 press the calibrations for the different strengths of current through the 



