478 Report on the Trials of Implements at Cardiff. 
movable jaw is suspended upon a pin, B, and is moved by the rocking lever, 
C, held by the pin, F, between the two toggles, D and E. The thrust is upon 
the lower part of the jaw, and is greatest when the lever is in a vertical 
position and the two toggles are in the same straight line. The pin, F, which 
gives support to the lever, is carried in two horizontal slots in the side frames. 
Good roads are one of the first requisites of good farming, but the scarcity 
of labour has of late made it very dilEcult to get the road metal reduced to 
a proper size at moderate cost. When every large quarry is provided with a 
good stone-breaker the work of the road surveyor will bo simplified and the 
cost of road-making much reduced. 
Fig. 39, — Blake's Stone-hreaker. 
The last on the list of Medals awarded is given for a simple and valuable 
contrivance for avoiding the loss of time and labour that frequently occurs in 
setting the portable engine to work. It is an easy matter to run the engine 
at once very nearly into the position required for driving a threshing-machine 
or a windlass for steam ploughing, but the last few inches of the adjustment 
often require an amount of pushing, pulling, and lifting, that on soft ground 
may strain the implements as well as men and beasts. If ever a Society 
should be established for the Prevention of Cruelty to Machines, a contrivance 
like this might well compete for a Medal. The object of the contrivance is to 
shift the position of the engine upon the fore and hind carriages without moving 
the wheels : this is done by transverse screws that can be easily fitted to an 
ordinary engine. Fig. 40 gives the front elevation of the engine — one of 
Clayton and Shuttleworth's make — a female screw is cut in the head of the 
bolt in tlie middle of the fore-carriage, a long screw of coarse pitch is tlien 
