282 Report on the Trials of Reaping Machines at Leamington, 
arm the share A, which passes under the ridge or row of potatoes, 
raising the tubers and the soil together ; and the mass is broken 
and separated in passing backward over a cylindrical cage B, 
revolving on a transverse axis in the direction shown by the 
arrow. The cage consists of rings with indented or waved 
Fig. 8. — Section illustrating the action of Aspinw all's Potato Digger. 
circumference, set at intervals along the axis ; or there may be 
two sets of rings, large and small alternately, the inner cage 
being driven at a higher speed than the outer one, as was the 
case in the machine tested at Birmingham. Thus the outer 
cage lifts and partially separates the earth and potatoes with a 
comparatively gentle motion, leaving a thorough riddling and 
removal of the potatoes from the soil to be completed by the 
more rapidly rotating cage within. A roller, C, of dice-box 
or hollowed form like the roller of a turnip-drill, presses down 
the tops or vines in advance of the share, being carried between 
two arms with gathering prongs, D, at liberty to rise and fall 
according to the height of the potato row. In the trial at Bir- 
mingham the machine was not once choked by the haulm, 
which was rank and green, but cleaned itself admirably, and the 
tubers were not at all bruised. The draught appeared to be 
easy ; and, in fact, the trial was a success. The price, 20/., was 
not deemed excessive. 
A silver medal was awarded to Messrs. Hayward Tyler and 
•Co., of 84, Upper Whitecross Street, London, for their Caloric 
Engine. 
As may be understood by the sectional cut (Fig. 9) given, the 
•engine consists essentially of a compression-cylinder A, and a 
power-cylinder B, with their respective pistons C D, and con- 
nections, and a regenerator H. The lower portion of the com- 
pression-cylinder A is kept cold by a current of water which 
circulates through the cooler E, which surrounds the lower 
