244 Dr. W. Marcet and Mr. R. B. Floris. An Experimental 



The observer, whose duty it was to read the thermometers, stood 

 up on a stool ready to work the regulators of the dynamos, and by 

 constant attention the temperature of the metal of the copper 

 chamber was not allowed to fall or rise beyond about O3 from the 

 initial reading. 



After an hour, measured to a second with the stop-watch, a last 

 reading of the thermometers was taken while at the same time a signal 

 was made to the person in the chamber by showing him a light, and 

 lie immediately closed the stopcock of the tube letting the melted 

 water into the flask. By this means the water collected was given 

 out exactly in one hour, the agitators were stopped, and the person 

 under experiment finally let out. As soon as the door was open, the 

 temperature of the ice water in the flask was recorded. 



The sublingual temperature when required was again taken at 

 that time, if it had not been determined in the last few minutes of 

 the stay in the chamber. 



The next process was to weigh the flask with the ice water and 

 thermometer, and by subtracting the weight of the empty flask and 

 thermometer, that of the melted ice was obtained. In one hour's 

 experiment the water from the melted ice amounted to rather over 

 1000 grams, but its weight varied on each occasion. The counters 

 in connection with the agitators were now read. 



This completed the data for the calculation of the calories re- 

 covered in the chamber. The calculation, a very simple one, is illus- 

 trated in the following table, which gives the particulars of one 

 experiment taken at random : 



Illustration of the Observations and Calculations required in one 



Experiment. 



Two preliminary Test Experiments with Agitators to determine Heat 



given out. 



Upper agitator. Lower agitator. 

 924,442 677,155 



735,640 494,300 





1st counters. readings 



{. initial ., 



Number of revolutions . . 188,804 



f Final readings . . 1,104,775 

 2nd counters < 



I Initial .. 924,444 



Number of revolutions . . 180,331 



182,85* 



852,831 

 677,155 



175,676 



Sum of revolutions squared. Calories found. 



1st 13,813 12,527 



2nd 12,674 12,138 



Means .... 13,244 



12,333 



