298 
Steam-digging Machine. 
break up the soil very fine to prepare it for immediate sow¬ 
ing, the wheels may be so set that the machine will move 
only 2 or 3 inches in each stroke of the diggers. If it is 
desired to break up the ground roughly and in large 
clods, so that the weather may penetrate it thoroughly, 
the machine may be set to dig at intervals of 9 or 10 
inches. It can also be so arranged that the diggers 
may penetrate from 6 to 12 inches deep, according to 
circumstances, and according to the nature of the soil. 
Various forms of diggers may be attached : the lower 
part may be in the form of a common spade, three¬ 
pronged fork, &c.; and if the ground is extremely hard 
or stony, they might be made to consist of a single bar 
of iron, like the end of a crow-bar. To enable the 
machine to pass on, though a large stone or root should 
obstruct the diggers, they are made sufficiently strong to 
bear the weight of the machine ; so that, if the digger 
cannot penetrate, it lifts the machine bodily, which enables 
it to pass on without injury. In stiff and moist soils it may 
be necessary to attach a plate of iron to the front of the 
machine in such a manner that the diggers as they come 
out of the ground would scrape against it, and clear 
themselves of earth. The machine, besides the two 
wheels which principally support it, has a small wheel 
at the end that goes first, so arranged that it may be 
turned by a lever, by which means the machine is guided. 
In the small machine which has been made, there are 
4 diggers in one line, taking a breadth of 4 feet at a 
time, so that in digging an acre the machine must pass 
over about 2 miles of distance. This would be a con¬ 
venient size for a 2-horse engine, and I think would 
dig 2 acres in 12 hours, with a consumption of fuel of 
14cwt. if wood is used, consuming tons of water in 
the same time: but this has not been tried. A 5- 
horse machine, which might dig 5 acres per day of 12 
