General Notices. 299 



shown in the plate. The one roller (y) turn the other (z) by the pitch-chains 

 (« a), the chief use of which is to keep the sheet of canvass from changing its 

 place by the revolution of the rollers. The canvass, from its gravity, would 

 slip clown upon the rollers as the machine moved forward ; and it would twist 

 upon them, by the unequal pressure to which it is exposed, by the cut corn 

 pressing unequally upon it. To prevent these derangements, there are loops 

 fixed to the canvass, which are made fast to the links of the chain, about 6 in. 

 apart; and there being an equal number of links in both the upper and lower 

 chains, and an equal number of teeth in the four pulleys upon which they 

 work, the canvass revolves uniformly, without being in the least deranged 

 by the many casualties to which it is exposed, b is the pole to which the 

 horses are yoked : it is made of wood, and is firmly fixed to the cross rails 

 upon the top of the frame : its length is ] ft. from its extremity to the frame 

 of the machine, c c are the swingletrees by which the horses are yoked : 

 they are yoked similarly to horses in a carriage, so as both to draw forward, 

 or push backward, at pleasure. Their heads, of course, are towards the 

 machine ; and, in appearance, they push the machine before them, but, in 

 reality, they are drawing the same as in the plough, d is a small rod of 

 wood, or helm, which the driver holds in his right hand, by the pulling of 

 which to him, or pushing it from him, he conducts the machine straight for- 

 ward. The dotted lines in the plate are a continuation of the pole with the 

 swingletrees and helm attached. The machine is turned, at the end of the ridge, 

 by the following contrivance : — The two wheels e e, in the body of the ma- 

 chine, are joined to the lever ff by an upright movable axle. The wheels are 

 similar to the two (c c) on the front of the frame : they have a strong iron axle, 

 which is made so long as to let the wheels conveniently turn, between the 

 crank-rod k and the frame of the machine. In order that this piece of the ap- 

 paratus may be used with advantage, the beveled wheel i is not placed upon 

 the middle of the main axle D, but about 1 ft. from the end of it, as is seen in the 

 drawing. This throws the crank-rod K nearer the side of the machine, thus 

 leaving plenty of space for the turning apparatus. In the middle of the 

 horizontal axle of the wheels e e there is an upright standard of iron, suffi- 

 ciently strong, and fimly joined to the horizontal axle. This upright stand- 

 ard or axle passes through the middle of the lever//" (which is of wood, and, 

 at this part, about 5 in. square), about 20 in. from the end of it. Upon the 

 top of the upright standard there is placed a segment of a wheel i, with the 

 teeth on the lower side, which is worked by a small pinion of 6 teeth 

 upon the end of the rod g g. This pinion is not seen in the drawing, as it is 

 completely concealed by the segment i. The rod gg, and the small pinion 

 upon it, are turned round by the handle h ; the pinion moves the segment i, 

 which, being firmly fixed to the upright standard, turns the small wheels e e 

 either way. When the machine is cutting, the wheels e e are put parallel to 

 the cutters, and in this position they assist the machine in passing a furrow, 

 without allowing the cutters to come in contact with the opposite side of it. 

 But, when the machine is to be turned round, they are turned with an angle 

 to the path of the machine by the handle h ; and the rod gg being fixed in 

 that position by a screw near the handle, the lever is then pressed down, and 

 fixed with a catch to the frame of the machine. In pressing down the 

 lever ff, the small wheels e e, which before were about 2 in. from the ground, 

 are pressed to the earth, about 2 or 3 in. below the natural level of the ma- 

 chine. Of course, the two front wheels c c are lifted 2 or 3 in. from the 

 ground, and the cutters considerably more, thus insuring them from acci- 

 dent while turning round. The machine now rests upon the two large 

 wheels b b, and the two small ones ee of the lever ; and the two front 

 wheels c c go for nothing, as they do not touch the ground. But the axle 

 of the small wheels e e being placed with an angle to the main axle d of the 

 large wheels b b, the machine will naturally turn round upon the horses 

 being moved slowly forward : of course, the greater the angle formed by the 



