CALIBRATION TESTS 



15 



Table 1. Results of earlier calibration tests of ergometer I. 

 [Experiments made in the respiration calorimeter at Wesleyan University, Middletown, Connecticut.] 



CALIBRATION TESTS OF 1911. 



An extensive series of calibration tests of ergometer I was carried out 

 at the Nutrition Laboratory in June and July of 1911. The details of a 

 single day's experiment, that of July 7, 1911, will serve to show the method 

 used in these tests. While the results of the experiments are usually 

 expressed in totals for 3 to 6 hours, the particular experiment selected 

 was run in a series of six 1-hour periods, and the individual hourly de- 

 terminations are given in table 2. Even when experimental periods are 

 longer than 1 hour, computations made on the hourly basis are frequently 

 of much value in indicating abnormalities in the course of an experiment; 

 usually these periods agree very satisfactorily with each other. 



The weight of water passing through the heat-absorbing system during 

 the experimental period and the rate of flow per minute are first recorded, 

 then the average temperature difference between the water entering and 

 that leaving the chamber, with a slight correction suggested as necessary 

 by Armsby 1 for the pressure of water upon the glass bulbs of the ther- 

 mometers, the final corrected temperature difference being also given. 

 Multiplying the weight of water by this corrected temperature difference 

 gives the heat measured in terms of large calories. A further correction 



1 Armsby, U.S. Dept. Agr., Bureau of Animal Industry Bui. 51, 1903, p. 34; Atwater 

 and Benedict, Carnegie Institution of Washington Publication No. 42, 1905, p. 134. 



