DESCRIPTION OF PLATES. 



PLATE XVIII. 



Fig. 224. A pair of friction wheels, supporting one end of the axis of a wheel. 

 P. 164. 



Fig. 225. The centre of the wheel A B, passing over the obstacle C, describes 

 the path DE; that of the larger wheel FG, the path HI, which is less steep. 

 P. 164. 



Fig. 226. The centre of the wheel A B describes the curved path C D, in passing 

 over the obstacle E, while that of the larger wheel F G has an angle at H. P. 164. 

 Fig. 227. The wheel A B, moving on a soft road towards B, has to overcome 

 the resistance of the earth at C. P. 165. 



Fig. 228. A section of the wheel of a carnage, a little dished, or inclined out- 

 wards. P. 166. 



Fig. 229. A B and C D being the straps or braces by which a coach is suspended, 

 if the centre of gravity be at E, F, or G, it must move, when the carriage swings, in 

 the curve passing through the respective point. P. 167. 



Fig. 230. The mode of harnessing two horses, so as to make them draw conve- 

 niently together : when either horse advances so far that the bar A B assumes the 

 position C D, the foremost horse has the disadvantage of acting on a lever equivalent 

 only to E F, while the other horse acts on EC. P. 167. 



Fig. 231. A sugar mill. The axis A is turned either by animal force or by 

 water : the liquor is collected in the trough B, and runs off in the channel C. The 

 openings D are for the purpose of adjusting the axes of the rollers. The canes are 

 supplied by the hands of the workmen. P. 170. 



Fig. 232. A glazier's vice. The vacuity in the middle shows the form of the 

 section of the lead which is drawn through it. P. 171. 



Fig. 233. A forge hammer, elevated by the plugs, projecting from an axis, 

 either at A, or more conveniently, at B, and thrown forcibly against the wooden 

 spring C. P. 171. 



Fig. 234. An engine for driving piles, on Vauloue's construction. The horses, 

 drawing at A, B, raise the weight C, held by the tongs D, fixed in the follower E, 

 which are opened, when they reach the summit, by being pressed between the 

 inclined planes F, G, so as to let the weight fall. At the same time the lever H is 

 raised by the rope I, and presses on the pin K L, so as to depress the lever 

 M N, and draw the pin O out of the drum P Q ; the follower then descends, and 

 uncoils the rope, its too rapid motion being prevented by the counterpoise R, 

 acting on the spiral barrel Q. The motion is regulated by the fly S, the pinion of 

 which is turned by the great wheel T. P. 173. 



Fig. 235. The rollers of the slitting mill. P. 1 74. 



Fig. 236. A simple plough. A is the coulter, for dividing the ground ; B the 

 share, fixed on the mould board C, for turning it to the right hand ; D is the rest, 

 and E, F, the handles. P. 175. 



Fig. 237. Section of a threshing mill. The corn is drawn in by the rollers or 

 feeders A, B : it is beaten by the revolving beaters C, D, and the straw is drawn 

 out by the rakes E, F, which discharge it at G ; the grain falling through the arched 

 bottoms H I, I G, which are formed like sieves. P. 178. 



Fig. 238. A corn mill, with some of the improvements made in America, by Mr. 

 Ellicott and Mr. Evans. The corn being poured into the funnel A, is conveyed by the 

 revolutions of a spiral B C, to C, whence it is raised, by the chain of buckets C D, 

 to be cleaned by the revolving sieve E, and the fan F ; it is then deposited in the 

 granary G, which supplies the funnel or mill hopper H ; this being perpetually agi- 

 tated by the iron axis of the upper mill stone, shakes it by degrees into the perfora- 

 tion of the stone ; it escapes, when ground, at I, and is conveyed, by means of the 

 carrier K L, and the elevator LM, to the cooler N, where it is spread on a large 

 surface : it passes afterwards to the bolter O, and is received in the binn P, from 

 whence it is taken to be packed in sacks or barrels. Q, represents the surface of a 

 mill stone, cut into furrows, in order to make it act more readily on the corn. 

 P. 179. 



