Figs. 6, 7, and 8, are figures of a chaff-cutting in. chine, which, under a variety of forms, has come info very general use. The original was constructed by \1 James Pike, who presented one to the Society of Ai many years ago. It has received successive improvc inents from Messrs Cook, Nailer, Winlaw, Macdougal and other implement makers, till it obtained the form given in Plate CXXXV. Fig. 6 is a front, and Fig. 7 a side elevation ; in which AAA is a cast-iron fly-w heel. with three curved arms, extending from its centre to the circumference ; and against these, 3 knifes b b b are screwed and adjusted by wedges behind, to apply faith against the end of the box ll, in which the straw or lia? is spread evenly and regularly. The spindle a, Fig. 7. of the wheel is supported in bearings at each end, one being screwed to the side of the chaff-box, and the othe • fixed upon a post II, which is attached to the frame_ K by blocks, and secured to it by braces I; so that it is yen firm and secure at a proper distance from the frame 1; The axis a has a worm, or endless screw. formed upo., it, which actuates the teeth of a wheel F, fastened upo•1 the end of the spindle of the lower roller in the chaff box. The upper roller is supported in a frame of iron c•, shewn separately in Fig. 8. This is attached to the box by centre pins at e c, and the arms ef, e f procee to the branches which carry the pivcts of the rugger g A bar f f unites the two sides of the frame ; and upon this a short lever operates to press down the whole frame, and thus hold the roller down forcibly upon the rtraw, and press it between it and the lower roller, so that it will be moved forward when the rollers are united round by the motion communicated to the worm-wheel of the lower roller. The upper roller is moved by a contrate wheel 1, on the extremity of its spindle. which is turned round by a long upright pinion m ; and this receives its motion by means of a similar contrate wheel 1 from the lower roller. By this means the upper roller is alien% s
kept in motion, let it rise as high as it will, in cons,.: quence of a great feed of straw being introduced be tween the two. The short lever, which, as before stated. depresses the upper roller and frame e f, is fixed upon an axis (1; on the end of which, a lever d c is fastened, and loaded at pleasure by a moveable weight c, which, like a steelyard, can be shifted at pleasure, to increase the pressure upon the straw. A piece of wood h, Fig. 8, is attached to the iron frame e f, and pressed down upon the straw, just before the place where the knife cuts the straw. The whole is turned round by one man working a handle B, fastened on the end of the main axis; and'it is stated by the inventor, that twenty-two bushels can be cut in an hour by this machine with one man. 'file rol lers which advance the straw, have diagonal ribs of iron projecting from them, as shewn at g, Fig. 8, which hold the straw fast ; and the lower roller has the same.
This machine is of small size, and being sold at a low price, is very generally adopted ; but the action is not by any means so good as that of the machine of Mr Salmon; and the rollers acting to advance the straw forwards all the time during the cut, causes a great friction on the back of the knives. Mr Passmore of Doncaster makes machines on Mr Salmon's plan, of a small size, in cast iron, which are cheap and effective : And Mr Braby of London has produced a simple machine, which is the old chaff-box provided with rollers to advance the straw ; and these are turned round by a ratchet-wheel, which is moved every time the knife is raised up to make a fresh stroke, and thus the straw stands still during the cut. (.1. F.)