HEATING BY HOT- WATER PIPES. 



165 



or tin-plate, they are better calculated to 

 disperse the heat than those of cast-iron 

 commonly used, which are, perhaps, ex- 

 cept in point of strength, the worst that 

 can be employed. They expose a smaller 

 surface in proportion to the water they 

 contain, than pipes of any other shape ; 

 and from the thickness of metal — never less 

 than three- eighths of an inch, and frequent- 

 ly more — they oppose a direct obstacle to 

 the ready transmission of the heat from 

 the water to the surrounding atmosphere. 



" No reservoir is attached to the appa- 

 ratus above described; but on a large 

 scale it would, of course, be necessary, the 

 quantity of water being small, and there 

 being no mass of brickwork to act as a 

 reservoir of heat. This purpose, however, 

 is evidently much better answered by a 

 cistern of water within the house than by 

 a boiler and brickwork, from which much 

 heat is dissipated in the back shed ; but 

 to prevent loss of time in applying the 

 heat in severe weather, it should be so 

 connected with the pipes that the water in 

 them may be sufficiently heated to warm 

 the house before it is allowed to pass into 

 the reservoir." 



Rogers mode of heating. — Experience, 

 according to Mr Rogers, led him to adopt 

 a conical form of boiler in preference to 

 the cylindrical one he commenced his 

 experiments with. He also abandoned 

 copper on account of its being corroded 

 in a few months by the sulphur dis- 

 engaged from the coke. He at first had 

 doubts as to the prudence of adopting 

 cast-iron, thinking that the unequal ex- 

 pansion might cause the boiler to crack — 

 not at all an unfrequent circumstance 

 when that metal is employed ; and also 

 that, on account of the greater thick- 

 ness required, that metal would be longer 

 Fig. 181. in heating than 



copper — a suppo- 

 sition entertained 

 by many, though 

 practically the dif- 

 ference is scarcely 

 perceptible. The 

 following is the 

 description in his 

 own words, taken 

 from the " Garden- 

 ers' Magazine," 

 xvi. p. 132 :— 



Fig. 181 " is a front view of the boiler 



as at present constructed of cast-iron : the 

 interior, a sugar-loaf-shaped cone (indi- 

 cated by the dotted lines, fig. 183,) being 

 the furnace, which is filled with fuel from 

 an upper orifice, a. A circular fire-grate 

 is fixed just within the bottom of the 

 boiler ; and the aperture b, seen in front, 

 is intended solely to remove clinkers 

 which may form, or fuel when the fire 

 is extinguished : at other times it is 

 closed with a fire-brick plug, and should 

 never be opened except when absolutely 

 necessary." 



Fig. 182 " is a side view of the boiler, 

 where it is represented as attached to a 



Fig. 182. 



range of pipes ; / and r are the flow and 

 return pipes, and d a flange for examining 

 and cleaning the boiler when necessary. 

 Into this flange is fixed a small pipe, 

 which, being connected upwards with the 

 supply cistern e, and downwards with the 

 cock or tap k, serves to fill and empty 

 the apparatus. The supply-cistern e acts 

 also as an expansion-cistern, to receive 

 the volume of water increased by heat." 



Fig. 183 "shows the most convenient 

 mode of setting the above, exhibited by a 

 front view. A solid base being built, with 

 an aperture in its centre open to the front, 

 as high as the desired depth of the ash- 

 pit, the boiler is fixed upon it, and the 

 brickwork carried up to its lower flange 

 or rim. The side walls should then be 



