Liverpool and Mandiester Railwaij. 327 



machinery. The objection to horizontal cylinders, founded up- 

 on the more rapid abrasion of the lower side of the piston by 

 the effect of gravity, is not found to have much force in practice. 

 In some carriages the piston rods are connected to the outside 

 of the two fore-wheels, but in the improved engines they are 

 connected to cranks on the axle of the carriage, in which case 

 the cylinders are placed below the boiler, and are quite hid 

 from view, as in Plate V. On these engines also the wheels 

 themselves are connected by rods, by which means the moving 

 power is applied to four wheels instead of two, which doubles the 

 adhesion of the carriage to the rails. The cross-head at the end of 

 the piston rod, working in a slide, produces the parallel motion. 

 I may add, that some experiments were made on the Liverpool 

 and Manchester Railway with Lord Dundonald's rotatory en- 

 gine, which were of so favourable a nature, as to induce the 

 Railway Company to construct a locomotive carriage on that 

 principle. I have not, however, heard whether their efforts to in- 

 troduce the rotatory system have proved successful. 



The fire-box, as in Plate V. letter a, consists of a double 

 casing of metal, with an intervening space of about 4 inches. 

 This space is filled with water, and has a free communication 

 with the boiler, of which it may be said to form a part. It has 

 a grated or ribbed bottom for holding the fuel, about nine square 

 feet in surface. The smoke-booc at letter c and {hejunnd at d 

 are made of iron, and are indispensable for catching the dust 

 and embers blown through the tubes, carrying off the smoke and 

 steam, and causing a draught for the combustion of the fuel. 

 In the improved engines, the waste steam is ingeniously blown 

 into the tender, and heats the water for the supply of the boiler. 



The framing in some instances is made of cast-iron, but more 

 generally of wood. It rests upon the axles, and supports all the 

 machinery, together with the boiler and its accompaniments. 

 Connected with it also are the springs for rendering the motion 

 as smooth as possible for the machinery. The carriages have 

 generally four wheels ; the " Atlas," however, and some others 

 have six. In some carriages all the wheels are of the same size, 

 and about five feet in diameter, while others have one smaller 

 pair of wheels about four feet in diameter. The naves and 

 rims are of cast-iron, and the spokes and tires of malleable 



