附 录Chaff cutterChaff cutter a mechanical device for cutting straw or hay into small pieces before being mixed together with other forage and fed to horses and cattle. This aids the animals digestion and prevents animals from rejecting any part of their food.Chaff and hay played a vital role in most agricultural production as it was used for feeding horses. Horses were extensively used in farming operations until they were replaced by tractors in the 1940s. The chaff box or cutter was a simple but ingenious device for cutting straw chaff, hay, and oats into small pieces - before being mixed together with other forage and fed to horses and cattle. Apart from being more economical than previous methods of feeding, this aided the animals digestion and prevented animals from rejecting any part of their food. Since the chaff box was made largely of wood (usually ash) with only a small amount of ironwork, it cost relatively little to make and, as a result, few farms, town or country stables were without one by the end of the eighteenth century. There were two sizes, one of heavy construction which normally resided in the darkened corners of barns or stables and another smaller model made of pine or similar wood which was portable. The barn version typically comprised of an open-ended, three-sided wooden trough between 3 foot 6 inches and 4 feet (1067-1220 mm) in length, 9 to 12 inches (229-305 mm) wide and 9 to 12 inches deep, mounted on either three or four legs approximately 22 inches (560 mm) high - giving an overall height of about 34 inches (863 mm). The rear leg or legs were sometimes taller than the front to tilt the trough forward to facilitate cutting. Both front legs of an early three-legged form were distinctly bow-shaped.To advance the bundle of hay or straw along the trough on all but the earliest models, a short-handled dwarf or chaff fork with between four and six tines was provided, attached by chains to the front of the box. These forks varied in width between 230-250 mm, depending on the inside dimensions of the trough. The tines were about 120 mm long. The front end was framed by a metal plate which looped over the top to provide a useful lifting handle. Below this a large knife was hinged diagonally to a single or double sided arm which extended pivotally from the base of one front leg and passed through the hollowed centre of the opposite leg. This allowed the knife to be moved up and down in an oblique cutting action, rather like a modern office guillotine. The plate stiffened the straw at the cutting edge as the sharpened blade passed close by. The early chaff knives had a scimitar like shape with a curved blade broadening towards a cranked wooden handle. Most ended their days with undulating edges. Scythe blades were often modified and used. From the 1860s most factory produced replacement knives were made with straight cutting edges varying in length between 20 and 34 inches with cranked or crosshead handles. At least nine large edge tool manufacturers produced them in numbers including Isaac Nash & Sons - who continued to advertise their best Crown chaff knives in the 1930s. The cutting position on some could be adjusted by moving the pivotal or hinge bolts into alternative holes drilled along the appropriate end of the knife arm. When not in use the knife rested in an open-ended bracket or stop situated half way down the opposite front leg. Knives were removed for thorough sharpening. Left-handed boxes were uncommon. Beneath the box a treadle, hinged to the knife arm or the adjacent leg, operated a wood block clamp situated inside the trough just behind the cutting edge. Its purpose was to compress the straw before cutting. The clamp was held by a narrow length of iron bar which extended through vertical slits cut in both sides. In pre-1800 form, this bar had looped ends from which ropes drew the clamp down on to the straw. But, in order to move the straw forward after each cut, the clamp had to be continually pulled up by hand using a piece of cord tied between the side and an iron staple located on top of the clamp. In a later development the clamp was perforated by a spindle and held between an inverted bracket joined to the treadle by a single hook or chain. By 1815 this type of linkage had been sprung by a length of spring steel or wood bolted under the feed end which automatically returned the clamp to its upper pre-compression position whenever the treadle was released. Some boxes, however, were equipped with a less widespread form of recoil springing, the principle of which probably originated in Europe. It comprised of two springy wooden poles fastened to the rear sides of the box, the overhanging ends of which were tied to the ends of the clamp bar. Another more durable method of springing was provided by a pair of side-mounted steel rods attached directly to the clamp spindle. These rods, under tension, were sl