on Agricultural Implements. 



627 



the supply of steam in the boiler of the driving'-engine was so adjusted that 

 the caJculated pressure was maintained during the trial. 



On reference to the tabular statement it will be observed that col. I 

 gives the " nominal horse-power,'' as stated by the makers; col. 2 gives 

 the horse-power corresponding to the power of steam actually employed 

 during the trial. The figures in these columns are for the most part iden- 

 tical, it being wished that the machines should be tried in accordance 

 with their designation — i. e. that a four-horse machine should be worked 

 by steam of four-horse power, &c. Some of the m.achines, however, 

 could not be worked without additional power, which is recorded against 

 them in col. 2. In col. 3 are given the revolutions made by the driving- 

 engine whilst threshing the allotted quantity of wheatsh eaves, viz. 2^ 

 cwt. Col. 4 shows the net pressure of steam at which each machine was 

 worked, and which had been previously calculated from the data above- 

 mentioned. Col. 5 shows the comparative time of performing the same 

 amount of work. This, it should be mentioned, is not the observed time, 

 but the time calculated from the registered revolutions of the engine. 

 The pressure of steam and the number of revolutions per minute which 

 were equivalent to the horse-power applied to each machine having 

 been ascertained, the whole number of revolutions made during the trial, 

 divided by the calculated number per minute, gave the number of 

 minutes required for the performance of the work at the specified power 

 and speed of drum. The figures in col. 6 represent the horse-power that 

 would have been required in each case to do the work in one minute ; 

 and show therefore, at a glance, the performances of the several machines 

 in respect of speed and power combined. The lowest figures represent 

 the most satisfactory results. Col. 7 show^s the quality of the work done 

 in respect of the three points of *' clean threshing," " broken grain," and 

 " state of straw.""' In each case a number is assumed to represent perfect 

 work, wiiich is considered to hear a proper proportion to the importance 

 of the point — so that the total number obtained by each machine, as shown 

 in the last column, may fairly represent the comparative goodness of the 

 work. 



The second trial was conducted in precisely the same manner as the 

 first, the only change being that barley was threshed instead of wheat. 

 Those machines only were allowed to compete which had acquitted them- 

 selves satisfactorily at the first trial. 



For the guidance of those who are not in the habit of examining tabular 

 statements, it may be useful to point out that the two columns to which 

 attention should be particularly directed are those numbered 6 and 7 — 

 the latter being the most important. On ascertaining by the " total " 

 number in col. 7 that a machine has done its work well, col. 6 should 

 next be consulted to ascertain whether under that head it received a high 

 or low figure ; if the former, it must be either slow in its performance 

 or heavy in its draught, but, if the latter, it may be inferred that it 

 had threshed wheat w^ell, and the second trial would be referred to to 

 ascertain its capabilities with respect to larley. An examination of this 

 kind will show that the machines which stand first in order of merit 

 are those of Messrs. Holmes, Hensman, and Garrett, and their perform- 

 ances having been in all respects satisfactory, medals w^ere awarded to 

 each of them. 



The shaker attached to Messrs. Holmes's machine was especially com- 

 mended as being very efficient, and yet adding little to the draught of the 

 machine. 



H. S. Thompsox. 



2 s 2 



