184 
Application of Sleam Power 
steering apparatus ; nevertheless, it was at work during the 
summer in the plains of St. Denis. A third and then a fourth 
machine were built by the trustees of the Beverley ironworks 
(under tlie management of Mr. Alfred Crosskill), and tested from 
time to time during most of the summer and part of the winter 
of 185G, and in the autumn of 1857, with many improvements in 
the strength and durability of the working parts. The fourth 
machine consists of a double-cylinder 12-horse engine, with 
framework and machinery, mounted upon a pair of very high 
broad-felloed wheels, with two smaller wheels in front for steer- 
age, and a fifth small wheel, also behind, for regulating the depth 
of the digging. Parallel connecting-rods, like those coupling the 
wheels of a railway locomotive, are used for transmitting motion 
from the toothed gearing at the fore part of the machine to the 
digging cylinder behind, allowing it to be lowered by toothed- 
rack, screw, &c., for any requisite depth of work, or raised above 
the ground for travelling. The digger is driven with a speed of 
some forty or fifty revolutions per minute, while the main carriage- 
wheels are made to rotate slowly, giving the machine a rate of 
progressive motion of about a mile an hour. The front wheels 
are liung on the same principle as chair-castors, enabling the 
steerage to be effected with great facility ; indeed, by setting these 
wheels at right angles, or nearly, to their. straightforward position, 
and actuating only one of the main wheels while the other is left 
stationary, the machine is turned short round in a circle the 
diameter of its own length, that is, about 15 feet. The digging 
cylinder is wide enough to project several inches on each side 
beyond the bearing-wheels, thus obliterating their track and 
allowing them always to travel on the unmoved ground; and the 
machine, being turned short round at each end of the field, passes 
alongside the breadth last cultivated, leaving two narrow headlands 
to be finally dug up, and tilling the most awkwardly angular 
corners without trouble or loss of time. The machine is also 
perfectly independent of horses, travelling of itself from place to 
place over moderately level roads or arable fields, and, when not 
used for cultivation, can draw a thrashing-box to a farmyard and 
drive it, or a corn-mill, or a saw-mill, or a pumping-apparatus, or 
whatever machine you please, by a strap from the engine flywheel. 
Now, as to the nature of the tillage performed. The digger 
consists of a hollow cylinder or barrel of boiler-plate iron, 2^ feet 
in diameter, hung horizontally across the back of the machine, 
and around this are fastened by bolts and nuts the cutters, some- 
what resembling Coleman's scarifying paring-shares, with curved 
stems. Tiiey can be quickly attached or removed, and are strong 
enough to enter the hardest ground, or encounter roots, small 
stones, !kc., without injury. When set to skim 3 inches deep, 
