Report on tlie Trials of Implements at Cardiff. 413 
kept as near as possible to the regulation pace of 1881 feet 
per minute, the number of the revolutions of each drum (re- 
corded in column 18) mainly depended upon the size of the 
drum rigger recorded in column 8. In column 6 we have 
the diameter of the drum in inches ; multiplying this by 3i-, 
we ascertain the periphery of the drum in inches : thus in the 
second machine we have 21 x 34-, giving a periphery of 66 
inches; this multiplied by the number of revolutions per minute 
in column 18 would give us the speed at which the periphery 
travels in inches per minute, and dividing this by 12 and 60 we 
get the rate in feet per second as given in column 19. The 
efficiency of the threshing proper, or the simple extraction of 
the corn from the ear, mainly depends upon the points indicated 
in columns 7 and 19, namely, the proximity of the concave to the 
drum, and the pace at which the drum-surface travels as it rubs or 
beats the corn against the concave. The concave being usually 
made in two parts, there are three points at which its distance 
from the drum may be adjusted — at the top, where the sheaf first 
enters, at the middle or junction of the two parts, and at the 
bottom, where the straw leaves the concave and passes on to the 
shakers, as shown in the section of the first-prize machine, Fig. 7, 
p. 422. During the trials the width of feed space was usually 
only measured at top, but in future trials it would be better to 
record the width at each point. The space should gradually 
contract from the top downwards. Thus in Marshall and Sons' 
machine. No. 5025, the width was ^ irch at top, ^ inch at 
middle, and inch at bottom, when threshing wheat ; and f , 
\, and \ inch respectively when threshing barley. The distance 
in every case was measured at the narrowest part, where the edge 
of the beater passed the projecting bar of the concave. 
Some of the machines were fitted with an index upon the out- 
side of the frame, showing at a glance the distance of the 
concave from the drum at each of these three points. We found 
the best of these indices to be the one on Messrs. Clayton and 
Shuttleworth's machine, and are strongly of opinion that every 
thteshing machine should be similarly furnished, the farmer 
would then have no difficulty in telling whether the concave had 
been properly adjusted for its work. 
In the speed of drum periphery (19) a striking uniformity of 
pace may be observed among the machines that did their work 
most efficiently ; it will be found, in every case but two, to 
slightly exceed the rate of a mile a minute. One of the earliest 
historical allusions to the art of threshing speaks of a wheel 
turned about upon the corn ; this was probably done at a rate of 
some 8 miles an hour ; the greater rapidity of this steam-driven 
age does the same work at 20 times that pace. 
