442 HENRY A. EOWLAND 



ceeding temperature. By interpolation in such a table we can then 

 reduce to even degrees. To compare the different results I have then 

 added to each table such a quantity as to bring the result at 20 about 

 equal to 10,000 kilogramme-metres. 



The process for each experiment may be described as follows. The 

 calorimeter was first filled with distilled water a little cooler than the 

 atmosphere, but not so cool as to cause a deposit of dew. It was then 

 placed in the machine and adjusted to its position, though the outer half 

 of the jacket was left off for some time, so that the calorimeter should 

 become perfectly dry; to aid which the calorimeter was polished with a 

 cloth. The thermometer and safety-tube were also inserted at this 

 time. 



After half an hour or so, the chronograph was adjusted, the outer half 

 of the jacket put in place, the wooden screen fixed in position, and all 

 was ready to start. The engine, which had been running quietly for 

 some time, was now attached, and the experiment commenced. First the 

 weights had to be adjusted so as to produce equilibrium as nearly as 

 possible. 



The observers then took their positions. One observer constantly 

 recorded the transit of the mercury over the divisions of thermometer, 

 making other suitable marks, so that the divisions could be afterwards 

 recognized. He also read the thermometers giving the temperatures 

 of the air, the bottom of the calorimeter thermometer, and of the wheel 

 just above the calorimeter; and sometimes another, giving that of the 

 cast-iron frame of the instrument. 



The other observer read the torsion wheel once every revolution of 

 the chronograph cylinder, recording the time by his watch. He also 

 recorded on the chronograph every five minutes by his watch, and like- 

 wise stirred the water in the jacket at intervals, and read its temper- 

 ature. 



The recording of the time was for the purpose of giving the connect- 

 ing link between the readings of the torsion circle and of the ther- 

 mometer. This, however, as the readings were quite constant, had 

 only to be done roughly, say to half a minute of time, though the rec- 

 ords of time on the chronograph were true to about a second. 



The thermometers to read the temperature of the water in the jacket 

 were graduated to 0-2 C., but were generally read to 0-1 C., and had 

 been compared with the standards. There was no object in using more 

 delicate thermometers. 



After the experiment had continued long enough, the engine was 



