280 



CASSELL'S POPULAR GARDENIXG. 



boilers, which can be kept slowly consuming the fuel 

 — coal, coke, or cinders — for twelve hours at a stretch 

 without attention. They can be had in various pat- 

 terns, and many of them are as neat and ornamental 

 as a front hall stove. 



Setting Boilers. — This is not less important 

 than a judicious selection of the boiler best suited 

 to its work. Many excellent boilers have been set 

 and taken down again as inadequate through being 

 improperly set, or placed behind 

 badly arranged piping. AATiere 

 amateurs or owners of one or two 

 houses employ native bricklayers 

 to set that universal boiler, the 

 " Saddle," slight mistakes often 

 lead to disappointment on the one 

 hand, and injustice on the other. 

 Now, as these boilers cannot be 

 surpassed, for the benefit of a 

 great number of the readers of 

 these pages the diagrams in Fig. 

 69 have been prepared, to show 

 how these small furnaces should 

 be built. After raising the founda- 

 tion to the proper height, the 

 bars are placed with their ends in 

 a line with the front of the boiler, 

 and their upper sides level with 

 the bottom ; the remainder of the 

 length of the furnace is made up 

 of fire-bricks. In front of the 

 bars comes the dead-plate, then 

 the furnace door, whose bottom is 

 on the same level. The distance 

 between the front of the boiler 

 and the door, nine inches, is made 

 up with brickwork, which forms 

 the general front. In i;his are 

 placed three soot-hole doors, as 

 shown in the figure. At the back 

 are placed two fire-lumps, the same size as the 

 boiler. They leave an opening opposite the centre 

 of the arch for the outlet of smoke and flame into 

 the flues, where they divide, and run right and left 

 along the sides of the boiler, as indicated by arrows 

 in the front view. Two cast-iron plates, a, built 

 into the brickwork, di^ude the lower from the upper 

 flue, but do not extend to the front wall by about 

 five inches, thus leaving a passage from the lower 

 into the upper flue, thence into the chimney. These 

 flues should be as deep as the size of the boiler will 

 allow, and the brickwork forming their sides some 

 four inches away from the boiler. The upper fire- 

 lump, d, checks the flame and keeps it back as long 

 as possible in contact with the inner arch of the 



boiler before it passes out and divides, on its way to 

 the two lower flues. The damper should be con- 

 veniently placed for regulating the draught, and the 

 chimney, although capable of being quite closed 

 near the throat, should be tall and roomy. Foui-teen 

 inches by nine makes a good chimney ; for larger 

 boilers it may be m.ore. 



\\Tien large boilers are purchased it is always 

 advisable to obtain plans and instructions for setting 



from the maker; 



The interior of all f m-naces should 

 be composed of fire-brick, in pre- 

 ference to iron, which is a rapid 

 conductor, and the most perfect 

 combustion takes place when the 

 fire is enclosed with fire-bricks 

 or Welsh lumps. They should 

 be constructed for a strong fire 

 when pressure is needed, and for 

 burning a smaU quantity of fuel 

 when little heat is required. All 

 furnace and ash-pit doors answer 

 best when made to fit close, with- 

 out getting out of order or warped 

 by the great heat of the fire. The 

 best for large apparatus are 

 known as Sylvester's construc- 

 tion, which have no hinges to 

 warp. The doors, which are 

 faced inside with fire-brick, move 

 on rollers on an iron rod, or slide 

 in a ledge or groove. The frame 

 of the opening projects outwards 

 towards the base, so that the door 

 partly rests upon it, and the more 

 it is moved the tighter it fits, an 

 arrangement which enables a 

 stoker to regulate the draught to 

 the greatest nicety. (See Fig. 67.) 



Slow Combustion Boiler. 



Site for the Boiler. — As 



all heated fluids naturally force 

 their way upwards, the boiler should always be 

 placed on a low level, and at the same time as 

 near its work as possible. It may be possible, 

 by means of circulating columns and cisterns, to 

 compel water to circulate below the boiler, but 

 only in extreme cases should a steady rise in the 

 pipes be departed from. In large and complicated 

 places a central position is very important, as long 

 mains are in this way avoided. There are, however, 

 many iiTegularly built places which formerly kept, 

 perhaps, twenty fires going, now heated from one 

 stoke-hole, where long mains cannot be avoided ; 

 and although some heat is lost, the loss is not so 

 great as might be imagined, provided the areas 

 are well built and carefully protected from wet and 



