22 Reynolds and Moorby, Equivalent of Heat. 



should be in pairs at 300 revolutions a minute, the loads 

 at first being — 

 Heavy trials 1,200 foot-lbs., about 70 H.P. on the brake 

 Light „ 600 foot-lbs., „ 35 H.P. „ 



The time of running one hour for each trial. The 

 thermometers in the inlet and outlet chambers, also the 

 temperature of the laboratory to be read every two 

 minutes and maintained as constant as possible, and 

 subsequently the thermometer on the stuffing-box and 

 brasses to be read every eight minutes, and the speed 

 gauge read every two minutes. The setting of the cocks 

 and the pressures in the supply pipe and artificial atmo- 

 sphere also recorded. All observations being recorded 

 in ink in a book, and kept distinct from any reductions. 



It was impossible to make trials simultaneously. And 

 as the possible opportunities were subject to the regular 

 work of the laboratory, in order to secure similar con- 

 ditions as far as possible, it was at first arranged that 

 each set should consist of at least four pairs of trials, 

 taken in such order that the four heavy trials were not 

 only made at hours of the day, but also on days in 

 the week similar to those of the corresponding light trials. 



Each such set of trials would afford means of 

 determining the approximate radiation -constant, and 

 show how far the radiation had been eliminated. 



In order to obtain still further definite assurance of 

 the elimination, it was arranged that, after consistent 

 results had been obtained in several groups of four pairs 

 of trials with the brake naked, the brake should be 

 covered with non-conducting material in the best way 

 practicable, so as to greatly reduce the radiation, at the 

 same time leaving it definite, and then similar trials 

 should be run. In this way, if the radiation could be 

 reduced to one-fourth part of that with the naked brake, 

 such error as there might be in the elimination with the 



