The attention of inventors and manufacturers of threshing-machines has not only been turned of late to the question of securing increased speed, but also of providing against the risk of accidents to those employed about the mills. The feeding of those high-speed drums which were getting so common was attended with considerable dan ger. Within the last few years, however, mills have been constructed, and are working well, with patent self-feeding apparatus. Considerable protection to life seems to have thus been afforded. The self-feeding apparatus consists of a covered hopper contain ing a shaking-board on which the sheaves are thrown sideways. Through this board, iron spikes curved like a fork or rake move forward and seize the unthreshed grain. A. second row of spikes regulates to a nicety the quantity of stuff reaching the drum at a time; and while the shaking-board is falling to let the grain come in contact with the drum, the first row of spikes progresses to catch a fresh supply. Some of the English threshing-machines fitted up in this way within the last few years thresh from 8 to 10 quarters of grain per hour, and perform their work in every respect satisfactorily.
The driving-power is wind, water, horse-power, or steam; the first of which is so very uncertain and unequal in its operation that it has nowadays been mostly super ceded by the others. Water-power is always desirable, and when it can be had in suffi
cient quantity or regularity, it is much to be preferred in point of economy, its mode of application to threshing being either by the ordinary machinery of the water-wheel (q. v.) or by Barker's mill (q.v.). Horse-power was the agent in most common use in the ear lier days of threshing-mills, the horses being yoked to beams attached to a vertical revolving shaft which communicated motion by means of beveled gear to the threshing machine. But it was found that this kind of work was very trying for the horses, and interfered considerably with the other work of the farm; and accordingly steam-power, as being more economical, has extensively superseded horse-labor, engines of 4 to 10 horse-power being generally employed. Portable threshing-mills and engines are very generally employed in England, and to some extent in Scotland, being thought by many to be more economical, from their saving the labor of transporting the crop from the stack to the barn; and from their adaptability to the requirements of a farmer who may rent more than one holding in a district. On the other hand, however, some prefer the fixed machine on account of cheapness and diminished liability to derangement.