134. 



Conical Boiler and h6t-*water Apparatus 



two bars, one supporting the fire-brick plug, and the other fitting 

 to the rim of the boiler to support a slate which closes the front 

 as inj%. 24. ff {Jig. 22.) is the chamber around the boiler, 

 filled with sawdust as a non-conductor of heat ; and a layer of 

 sawdust extends over the top of the boiler, under the slate slab 

 g g, which is fitted over the brickwork, an aperture being cut in 

 it to allow the throat of the furnace to pass through. 



JFzo-. 25. ffives the same view 

 farther completed : the front of 

 the chamber is closed with a slab 

 of slate, and on the slab which 

 covers the boiler is erected a chim- 

 ney, having a feeding-door, through 

 which fuel is supplied, placed in its 

 sloping face directly over the mouth 

 of the furnace. This chimney must 

 not exceed 4 or 5 feet in height, and 

 its area must in no case exceed the 

 area of the mouth of the furnace. 

 That here represented, viz. a brick 

 base, with a piece of 4-inch iron 

 pipe about 3 ft. in length, will 

 probably be found most conve- 

 nient, unless a movable chimney 

 be preferred. This chimney should 

 be fitted with a damper just below 

 the iron part, to give greater com- 

 mand of the draught. The aperture 

 of the boiler, which is closed with 

 fire-brick, and the front of the ash- 

 pit, should also be closed by a door or blower, having a regulator 

 to admit or exclude draught. A blower is preferable to a door, 

 as hinges are always liable to rust, and then break or strain ; 

 and it is important to be able to close the ash-pit pretty accu- 

 rately. 



JFig. 26- shows the relative position of the boiler and pipes, and 

 the mode of attaching and arranging them. In the first place, 

 the whole of the pipes should, if possible, be above the boiler. 

 One foot is sufficient, but when convenient, the higher the bettei'. 

 When 2- or 3-inch pipe is employed, the pipes may rise uniformly 

 about 1 in. in 20 ft. from a and ^ to c; on which, being thus the 

 highest point of the pipes, an air-cock is placed. But, if 4-inch 

 pipes be employed, it is better that a should be the highest point, 

 and the air-cock placed there; and that the pipes should fall uni- 

 formly 1 in. in 20 ft. from a to c, and from c to b: indeed this is 

 generally the best arrangement, whei'e not inconvenient. From b 

 the return-pipe r should descend either perpendicularly^, or with 



