558 



Report on the Exhibition of Implements 



powers. The consulting engineer, however, who watched the 

 trial with great care, discovered that though the steam was con- 

 stantly at the same pressure, some machines were able to obtain 

 a greater quantity of it than others, and that this depended on the 

 size of the driving puUy, which varied in different machines, and 

 thus enabled some to obtain, as it were, a greater number of 

 measures of steam than others. This trial, therefore, was not 

 quite conclusive, but it enabled the judges to select seven of the 

 best for further trial, and the following mode of obviating the 

 above-mentioned inequality was adopted : — Two steam-engines 

 were employed as before, and their boilers connected by a pipe, 

 in which was a cock which regulated the supply of steam from 

 the boiler which merely generated steam to that belonging to the 

 driving engine. The working engine moved at equal velocities in 

 all the experiments, consequently the machine requiring least 

 power was the one which worked with steam of the lowest pressure 

 in the second boiler. The plan adopted, therefore, was to record 

 the pressure of steam which was required to drive each machine, 

 as indicated by a pressure gauge (see Table D). 



Table D. 



Col. 8 gives the actual pressure of steam expressed in its equi- 

 valent horse-power ; col. 9 gives the time of threshing 100 sheaves 

 of wheat, and multiplying the two together we obtain a result which 

 expresses the comparative expenditure of power in each case ; 

 this is given in col. 10. The quality of the work is shown in 

 cols. 5, 6, 7. The numerals in col. 7 refer to the proportion of 

 broken grain found amongst the threshed corn ; Hensman's 

 machine, which is marked I, having the fewest broken grains, 

 the rest following in the order of the respective numbers. 



