Report of the Trials of Ploughs, Harrows, Sfc. at Hull. 549 
tion, is shown jointed by a bolt or pin, d, to the axictrees, e, of the wheels ; 
whereas in the implement shown at Hull, this screw is quite separate from 
the wheels, and terminates in a wooden roller, so that when the screw is 
lowered the roller takes the ground, and the wheels are raised with the frame. 
(/ is a pinion mounted in bearings on the socket b, gearing with the revolving 
screw, h is a worm-wheel keyed on to the axis of the pinion c/. The worm, i, 
gears into the worm-wheel, and is connected by a universal joint or coupling 
with a rod, /, extending back to the handles, and i^rovided with a winch-handle, 
Fig. 27. — Elevation of the front portion of Fison's Double-furrow 
Plough, No. 2997, 
by turning which the revolving screw is actuated, either for altering the deptii 
or taking the ploughs up at the headland. I is a worm-wheel, through which 
the revolving screw passes, also carried on the socket b, which is enlarged at 
2 o 2 
