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 AGRICULTURAL Potatoes are, perhaps, most often dug by hand, but there are also machines and implements provided for this purpose. One of the simplest of potato diggers (Fig. 30) consists of a double plough, to each wing of which are secured rearwardly extending fingers. As the plough is drawn through the field, the potatoes are thrown up, and as they slide over the fingers the loose earth is sifted through, while the potatoes fall off at the rear upon the surface of the ground, from which they are picked up by hand.

Fig. 31.—Potato digger. A slightly different form of digger is shown in Fig. 31. This plough throws up the potatoes like the former one, but turns them off on each side, where they fall upon a floating frame composed of steel rods, which are caused to vibrate by the inequalities of the ground, sifting out the earth and leaving the potatoes on the surface.

Fig. 32.—Potato digger.

MACHINERY

tion made so great a change. Most of the grain was then harvested by machines cutting by a reciprocating knife and throwing the grain upon a travelling canvas apron, which delivered it to a second elevator apron carrying it over the driving wheel, where it was dropped upon a table and bound by an attendant. These machines were furnished with a divider at the end of the cutter bar for separating the grain to be cut from the standing grain, and also with a reel which pressed forward into the standing grain and pushed it back to present it properly to the cutter bar. All these are essential features of the modern harvester. About 1873, what was probably the first commercially successful automatic self-binding harvester was brought out in the Locke wire binder. This was extensively used for several years, and wire binders were also built by other manufacturers, but there were serious objections^ to their use, principally on account of pieces of the wire being carried into the threshing machines and even into the flour-mills, where, by contact with the rapidly moving machinery, they were likely to cause fires. The attention of inventors was then turned to the twine binder, but although some of the earliest attempts at grain binding were made with twine, even antedating the wire binders, it was not until 1879 that the Appleby patent, under which most of the self-binding harvesters of to-day are built, wras taken out; and it was not until several years later that they came into extensive use. Some of the most important parts of the binder had been invented before’ the Appleby patent, such as the automatic trip which regulates the action of the binder, invented by Gray in 1858, and the knotting bill and revolving cord-holder, patented by Behel in 1864. For various reasons, however, none of these inventions went into use until they were embodied in the Appleby machine. The self - binding harvester is probably the most ingenious and interesting of all agricultural machines, and will be briefly described. Fig. 33 shows a rear view of the selfbinding harvester. As already explained, the grain is bent over and presented to the reciprocating cutter bar by means of the revolving reel, and is then conveyed by the apron and elevator over the master wheel and discharged upon the downwardly inclined binder table.

A more complicated form of potato digger is shown in Fig. 32. This machine is designed to be drawn by a pair of horses, and carries at its forward end a powerful scoop, which takes up the earth and potatoes, delivering them upon an endless carrier driven from the wheels of the machine. This carrier is composed of rods, and is given a vibrating motion by which most of the earth is sifted out, and the potatoes are discharged upon a second carrier Fig. 33. —Self-binrliiig harvester. which completes the operation. As the grain flows from the elevator, the butts are at The scoop can be adjusted by a suitable lever to dig at the front of the machine and are evened up by a device any desired depth. called a butt adjuster, shown in Fig. 34, which is conGrain Harvesters. nected to a crank at its upper end and guided on a rod at Twenty-five years ago grain was harvested by machines, its lower end, being thus given an elliptical movement and but they were very different in character from those now patting the ends of the grain, thus squaring the butt of in use, and in no class of agricultural machines has inven- the sheaf.