550 Report of the Trials of Ploughs, Harroics, S^-c, at Hull. 
the upper part, as shown in Fig. 29, to receive the boss of the worm-wlieel, 
and provided with screws, l^, working in a groove to retain the wheel in place 
and allow of its being rotated independently of the socket 6'. The worm- 
wheel, I, is fitted with a gib-key, m, received in a corresponding key-groove 
formed longitudinally in the revolving screw, to allow of the latter turning 
with the wheel, I, and yet allow the latter to move with the socket freely up 
and down in the screw or rack. A worm, n, gears with and operates wheel I, 
for guiding the wheels /. The worm is also connected by a vmiversal joint 
with a rod extending back to the handles, and similarly provided with a winch- 
handle ; both the friction-wheel and the steerage-wheels have bevelled edges, 
Fig. 28. — Plan of the Front Portion of Fison's Douhlefurroio Plough, 
No. 2997. 
and the former is set at an angle. Strength is gained by the bodies being split, 
with -wings attached on different sides of tlie beam seen in Fig. 30. The 
coulter attachment is somewhat i^eculiar ; the centre of the clip being slightly 
rounded allows sufficient adjustment of the coulters by the set screws. The 
Judges were by no means favourably impressed with this complicated arrange- 
ment, and do not expect to see it brought into general practice. , 
