BOILERS FOR STATIONARY ENGINES.

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corresponding lugs. The joint is made with a composition ring, oflead and tin, dropped into the recess, and then the screws aretightened; this joint is capable of sustaining as great a pressure asthe tubes, and can be made and re-made at any time without injury.

Fig. 14.—Water-tube Boiler, a, Furnace. B, Tubes. c, Flue. d, Division plate. e, Damper.f, Steam receiver. g, Stop valve. H, Safety valve.

The upper ends of the tubes have short pieces of wrought-ironwelded gas pipe, tapped into the end plates, for taking away thesteam to the main pipe, which is placed horizontally. Upon themain steam pipe smaller pipes are fitted, and connected to the smallgas pipes from each generator; thus the steam flows along them intothe large pipe, to which is fixed the safety-valve and the pipe tothe steam cylinder. All the parts are so arranged that they canexpand freely, without disturbing the joints. The oven has adivision plate strongly ribbed; by this means the flame impingeson the bottom halves of the generators, and passing along the tophalf goes to the chimney.

Another arrangement of water-tube generators has simplywrought-iron tubes, with cast-iron ends, secured with long boltsinside of the tubes, having the feed pipes joining together at thebottom; similar pipes are situated at the top of the tubes for thesteam, these lead into one main steam pipe, the whole beingencased in suitable brickwork. All the parts in this arrangementare well protected, only the plain parts of the tubes being exposed

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