Rcj)ort on the Trials of Implements at Cardiff. 415 
From the results of the steam-cultivating machinery at Wolver- 
hampton in 1871, we learn that the soil moved weighed 190 tons 
inch deep per acre ; if all the work expended in ploughing 
inches deep, harrowing, &c., were equal to two ploughings, 
tlien the foot-lbs. spent in cultivation per acre would be 
I'JO tons X 10 inches x 2240 lbs. x 20 foot-lbs. = 85,120,000 
foot-lbs. per acre, or nearly 6 times as much as the threshing. 
The two most important columns in the table are undoubtedly 
22 and 42 ; the latter gives us the comparative perfection of the 
work done by each machine, the former shows the power which 
the machine absorbed in performing that work. The best ma- 
chine (so far as the trial went, and apart from the question of 
strength and convenience of construction) would be the one that 
gained the highest points of merit at the smallest expense of 
power. 
After each machine had finished its work it was run empty 
for 3 minutes ; the power required to drive the empty machine 
is recorded in columns 12, 13, and 14. 
Before proceeding to speak of the performance of the separate 
machines, it may be well to note the general information to be 
derived from an inspection of Table I. 
Comparing columns 13 and 21, we observe that a very large 
proportion of the power employed is expended in driving the 
empty machine. This proportion varies from 52 per cent, in 
P. and H. P. Gibbons's machine to the extraordinary amount of 
more than 77 per cent, in Nalder and Nalder's machine. The 
lowest power required to drive any empty machine in this class 
exceeded 6J horse-power. 
Had there been time to do so, it would have been interesting 
to have ascertained by the dynamometer how this power was 
distributed throughout the machine ; there would be little diffi- 
culty in doing so with the machine run empty, and as the drum 
is probably the only part that takes much more power when at 
work than when running idle, we might approximately have 
ascertained how the full power was divided. A great uncer- 
tainty upon this point appears to prevail among the makers. 
One of the chief makers estimates the work as absorbed thus — 
4-lOths by the drum, 4-lOths by the straw-shakers and caving- 
riddle, and 2-lOths by the other parts of the machine. If this 
estimate is correct for the machine when at work, we may con- 
clude that fully one-half of the power required to drive the 
machine when empty is absorbed by the straw-shakers and 
caving-riddle, whose sole duty is to separate the short and long 
straws from the chaff and grain that have been mixed up with 
them after the latter has been extracted from the ear. Both 
shakers and riddle are usually driven by cranks ; and these crank- 
