HEATING BY HOT-WATER PIPES. 



167 



outside casing 

 openings, one on 

 Fig. 184. 



cast upon it, with two 

 each side, called the 

 ingress and 

 egress pipes ; 

 the one convey- 

 ing the cold 

 water, and the 

 other taking 

 away the warm, 

 which causes 

 the circulation 

 within the cis- 

 tern ; while the 

 third case or 

 outside cover- 

 ing is placed 

 about 4 inches 

 ¥ from the double 



IIL covering, leav- 



ing sufficient 

 room for a continued current of air to pro- 

 ceed into the chamber to be heated. It is 

 here where so many 

 blunder. Air ought 

 not to be roasted or 

 boiled; it ought to 

 be gradually heated 

 to a certain temper- 

 ature, and that tem- 

 perature must not 

 range beyond 85° to 

 95°:" MrRettie tak- 

 ing summer heat at 

 75°, which is the tem- 

 perature he aims at 

 producing in struc- 

 tures heated upon his 

 principle. On the cut 

 a steam gauge-tube 

 of glass will be seen, which will show at 

 all times the height of water in the boiler 

 and cistern; the draught and consequently 

 the combustion of fuel are regulated by 

 a well-contrived air-tight door and ash- 

 pit register. 



For heating greenhouses and conserva- 

 tories, where a more powerful and more 

 permanent apparatus might be found 

 difficult to place, this would be found a 

 useful substitute, as for such purposes it 

 might be fitted up in a portable state, 

 having the pipes attached to it by union 

 or flange j oints. To be of use as a radiator 

 of heat from its sides, or for heating air 

 made to pass between the outer casings, 

 it would require to be placed inside the 

 house. 



Fig. 186. 



Sampsons mode of heating. — The spiral 

 boiler, of which the annexed cut, fig. 186, 

 will give a very per- 

 fect idea, will be seen 

 from its construction 

 to possess a very im- 

 portant advantage 

 over most others. 

 The fire is placed un- 

 der the boiler, as in 

 most other cases; but 

 the smoke and heat 

 which, in others, ra- 

 pidly pass off in the 

 direction of the flue 

 or chimney, in this 

 pass upwards through the boiler, and for 

 a considerable way above it, around which 

 the spiral portion of the boiler is con- 

 tinued, abstracting the heat from the flue 

 as far as the set-off of the flow-pipe. The 

 direction of the flue is indicated by the 

 arrows; a is the place for lighting the fire; 

 b hole ; c flow-pipe ; d return-pipe ; e cy- 

 lindrical feeder for fuel, with air-tight 

 cover. The simplicity of its construction 

 enables any mason to fit it up with the 

 greatest ease ; indeed, all that is required 

 is merely to enclose it within a casing of 

 brickwork. 



Cottam and Hallen's system — Figs. 187 

 and 188. — These highly respectable en- 

 Fig. 187. 



gineers were amongst the earliest im- 

 provers in heating by hot water, and their 

 boiler is considered to this day as being 

 amongst the most effective. It is of the 

 horse-shoe shape, and forms the roof of 

 the fire-chamber, thereby lessening the 

 amount of building, and that in a part of 

 the furnace which, in general, is the first 

 to give way. The edges of the boiler are 

 set upon brickwork, and the heat may 



