OF THE MECHANICAL EQUIVALENT OF HEAT. 
371 
amounting to 3' 3, arose from the thermal effect of the fall of water from one vessel to 
the other. Hence the final result for the capacity of the calorimeter, appendages, and 
thermometer, is 4842 - 4. 
I thought it desirable to test this result by obtaining the sum of the capacities of 
the materials which composed the calorimeter. I had in my possession cuttings from 
the same sheets of brass that were used in the manufacture of the vessel and its 
paddle. These were formed into a compact bundle. 
A copper vessel, A (fig. 6), filled with water, had a narrower vessel, C, immersed in 
it, to the bottom of which the material experimented on was let down by a fine wire. 
A Bunsen burner, b, kept the water at a constant temperature for not less than three 
hours, a continual agitation being given by revolving the stirrer s, formed on the 
principle of a screw propeller. The temperature having been noted, the material was 
rapidly lifted by the thin wire, and transferred to a small copper vessel, Y, filled with 
distilled water, and furnished with a thermometer and stirrer. After 5 m , which time 
was required for the equal distribution of temperature, the immersed thermometer was 
read off, and its observation was repeated each succeeding minute for some time, in 
order to obtain the cooling effect of the atmosphere. * The following is a table of the 
results. The weight w of the bundle of brass was 2951 *6 grains. 
* The method first employed was the opposite one of plunging the material at the atmospheric 
temperature into a small vessel filled with hot water, and observing the temperature of mixture. The 
following specific heats were obtained by that method with brass and copper : — 
Brass. 
Copper. 
•09200 
"09516 
•08734 
•09183 
•08945 
•09295 
•09232 
•08794 
•08734 
•08969 
•09197 
The wide discrepancy between the several results is owing to the great effect of the atmosphere on the 
small vessel, necessitating an absolute uniformity of stirring in order to give true temperatures. 
