Transactions of the Horticultwal Society/. 



185 



hence, by putting a twentieth part, in addition to the surface required for 

 the house, through a proper reservoir of water, it will be slowly raised to 

 nearly the same temperature as the water in the pipes, and return its heat 

 to the house as soon as the fire ceases to keep up an excess of heat in the 

 pipes. Fig. 29. shows such an arrangement, where c is the cistern with part 

 of the pipe passing through it. 



"21. There is very little strain on the boilers of hot-water apparatus, 

 except in cases where there is much difference of level; and as these rarely 

 occur, consequently they may be constructed in the best mode for applying 

 heat ; which is most effectively done by having as much bottom surface as 

 possible with a boiler of a given capacity. For burning a bushel of coals per 

 hour, the area of the fire-grate should not be less than 8 nor greater than 

 16 square feet ; and the bottom surface four times the area of the grate, 

 with 32 ft. of side flue ; and a considerable advantage results from adopting 

 the larger proportion for the grate and bottom surface, on account of the 

 fire requiring less attention. 



" 22. The forms of boilers may be varied in a considerable degree, pro- 

 vided the above quantity of surface receives the effect of the fire. A 

 boiler in the form of half a hollow cylinder, affording a great quantity of 

 fire and flue surface, is made by Messrs. Bailey (^g. 25.), and a bottle- 

 shaped boiler (7%. 20.) is made by Messrs. Cottam and Hallen, which has 

 a considerable quantity of fire and flue surface, compared with its capacity ; 

 both these are, therefore, well adapted to cases where only a small reserve 

 of heat is required for night. The variation of the Scotch distiller's boiler ' 

 (Jig. 27.) is also a good form for maintaining the supply of heat to the 

 house, while a separate reservoir is warmed by part of the pipes. Another 

 mode ( Jig. 28.) of obtaining a large portion of fire and flue surfiice to a 

 small capacity may be adopted ; but complicated forms have little to recom- 

 mend them, and are expensive, except when so small as to be cast in iron ; 

 because the fire should be partially surroumled by slow conductors of heat 

 to prevent the dissipation of heat being too rapid, and to render the com- 

 bustion of the fuel perfect, and, consequent!}', effective ; hence, a fire-place 

 surrounded on three sides by brick is better than one in the middle of the 

 boiler. 



" 23. The best mode of regulating the fire is by means of a door to the 

 ash-pit, having a register, first suggested by Dr. Black, and afterwards put 

 in practice by Count Rumford. 



" 2i. 1 have now considered the most important points in the construc- 

 tion of a hot-water apparatus, and have shown that other fluids maybe 

 applied as well as water, when a more intense heating surface is desirable; 

 and that a reservoir of heat may be obtained without having to wait till a 

 large mass of water be heated before the heat has any effect on the house ; 

 and these, I hope, will be of some use in the application of this method of 

 distributiuff heat." 



