414 Report on the Trials of Implements at Cardiff. 
Should any of our readers be not quite familiar with tl 
expression " foot-pounds of work done " at the head of colun 
20, they may find a simple illustration useful. In raising wat 
from a well the amount of work to be done depends upon tiA 
quantities — the number of pounds that the bucket of water weigh 
and the number of feet through which that weight has to 1 
raised — 200 lbs. raised from a well 100 feet deep would consun 
the same power as 100 lbs. raised 200 feet. By multiplying tl 
feet by the pounds in each case, we obtain the same numbe 
20,000 foot-lbs. of work done. Now, in the case before us, tl 
driving-belt running at the rate of 1884 feet per minute corr 
sponds to the well-rope, and the net strain on the belt corresponc 
to the weight of the bucket of water ; for instance, in Claytc 
and Shuttleworth's first run the average net strain on the be! 
as proved by the dynamometer, was about 193 lbs., i.e. it w; 
sufficient to have raised such a weight vertically. Now, 193 lb 
multiplied by 1884 feet would give us 363,612 foot-lbs. < 
work done per minute, the exact quantity being 363,35 
foot-lbs. 
Since the power of a horse is estimated as equal to 33,000 foi 
lbs. of work per minute, the average horse-power used is obtaine 
by dividing 363,351 by 33,000, and is entered in column 2 
as 11*01. Since the machine ran for 18"8 minutes (colum 
17), the total work clone was 363,351 x 18-8, or 6,836,000 fo( 
lbs. entered in column 20. Column 20 thus gives us tl 
means of comparing the total power required by each machir 
for threshing 1 ton of sheaf-corn ; but since all the trials wei 
not made with 1 ton, only 15 cwt, of barley, and 10 cwt, of oa 
having been used in the third trial, we need a further calculation t 
enable us to compare accurately the power respectively require 
for threshing wheat, barley, and oats ; this we obtain in colum 
22, where the result oi dividing the foot-lbs. of work dor 
(20) by the pounds of sheaf-corn threshed in each case (16) 
entered. We here learn that for the threshing of each poun 
of sheaf-corn a power of from 2323 to 3137 foof-lbs. was n 
quired. In other words, we may say that if any quantity of coi 
were raised to a height of a little over half a mile, it would i 
falling produce a force which, if properly utilized, would suffi( 
to thresh itself. 
It may here be interesting to compare the power require 
for threshing a crop with the power expended in cultivatin 
the soil for the same crop. Suppose the crop threshed to I 
one of 4 quarters per acre, the grain, at 63 lbs. per bushel, woui 
weigh 2016 lbs., and the straw about twice as much, the shea 
corn from one acre would weigh 6000 lbs., and the foot-lb 
necessary to thresh it would be about 6000 x 2500 = 15,000,(»0( 
