(190.)

The Novelty, of Messrs. Braithwaite and Ericson, is represented in fig. 92.; and a section of the generator and boiler is exhibited in fig. 93.; the corresponding parts in the two figures are marked by the same letters.

Fig. 92.

A is the generator or receiver containing the steam which works the engine; this communicates with a lower generator B, which extends in a horizontal direction the entire length of the carriage. Within the generator A is contained the furnace F, which communicates in a tube C, carried up through the generator, and terminated at the top by sliding shutters, which exclude the air, and which are only opened to supply fuel to the grate F. Below the grate the furnace is not open, as usual, to the atmosphere, but communicates, [Pg350] by a tube E, with a bellows D; which is worked by the engine, and which forces a constant stream of air, by the tube E, through the fuel on F, so as to keep that fuel in vivid combustion. The heated air contained in the furnace F is driven on, by the same force, through a small curved tube marked e, which circulates like a worm (as represented in fig. 93.) through the horizontal generator or receiver; and, tapering gradually, until reduced to very small dimensions, it finally issues into the chimney G. The air in passing along this tube, imparts its heat to the water by which the tube is surrounded, and is brought to a considerably reduced temperature when discharged into the chimney. The cylinder, which is represented at K, works one pair of wheels, by means of a bell-crank, the other pair, when necessary, being connected with them.

Fig. 93.

In this engine, the magnitude of the surface of burning fuel on the grate-bars is less than two square feet; the surface exposed to radiant heat is nine and a half square feet; and the surface of water exposed to heated air is about thirty-three square feet.

The superiority of the Rocket may be attributed chiefly to the greater quantity of surface of the water which is exposed to the action of the fire. With a less extent of grate-bars than the Sanspareil, in the proportion of three to five, it exposes a greater surface of water to radiant heat, in the proportion of four to three; and a greater surface of water to heated air, in the proportion of more than three to two. It was found that the Rocket, compared with the Sanspareil, consumed fuel, in the evaporation of a given quantity of water, [Pg351] in the proportion of eleven to twenty-eight. The suggestion of using the tubes to conduct through the water the heated air to the chimney is due to Mr. Booth, treasurer of the Liverpool and Manchester Railway Company.