1 32 Conical Boiler and Jiot-'water Apparatus 



Art. XII. Description of the Conical Boiler and hot-lvaier Apparatus 

 invented by John Rogers, Jun., Esq., F.R.S. Communicated by 

 Mr. Rogers. 



I HAVE much pleasure in furnishing you with a description 

 of my conical boiler, of which you are pleased to express so 

 favourable an opinion. The apparatus, as at present constructed 

 in cast iron, is the result of a series of experiments, which have 

 engaged my attention at intervals during the last five years. 

 My first attempts were made in 1835, with a cylindrical boiler of 

 tinned iron, of which an account was published in Paxton's Ma- 

 gazine of Botany, for March, 1836. The experience thus attained 

 led me to adopt a conical instead of a cylindrical furnace ; and, in 

 a paper published in the same work, in March, 1837, my boiler 

 had assumed very nearly its present form. Various difficulties, 

 however, arose in the construction of the apparatus. Copper, 

 the material which I had employed in my second boiler, in the 

 hope that it would prove durable, was corroded in a few months, 

 by the sulphur disengaged from the coke ; while the expense and 

 difficulty of casting such peculiar forms in iron deterred me 

 from employing that material, especially as it was a matter of 

 considerable doubt whether its unequal expansion would not 

 cause such a boiler to break, or become leaky. At length, 

 after some other unsuccessful experiments which it is unneces- 

 sary to detail, the ingenuity and perseverance of Mr. Shewin, 

 an ironmonger of this town, have succeeded in overcoming the 

 difficulty of casting in iron, and a boiler has been produced 

 which combines strength and solidity with the advantages pre- 

 viously attained. The only point in which the iron is inferior to 

 copper is, that the greater thickness of the metal does not allow 

 the heat to be transmitted from the fuel quite so rapidl3^ In 

 practice, however, this is scarcely perceptible, and is far more 

 than compensated by the superior strength, economy, and du- 

 rability of the iron boilers.- • Indeed, I believe that those in 

 copper could never have been made generally useful ; for, besides 

 their liability to wear out, on which experience a little varies, 

 they were very easily injui'ed by rough usage. 



As many of your readers are probably unacquainted with the 

 apparatus, I shall endeavour to give a description of it in its pre- 

 sent form, with such plans and particulars as may enable them 

 to judge how far it is applicable to their purposes, and, if neces- 

 sary, to erect it themselves. 



Fig. 23. is a front view of the boiler as at present constructed 

 in cast iron. The interioi', a sugarloaf-shaped cone (indicated 

 by the dotted lines), being the furnace, which is filled with fuel 

 through its upper orifice (a). A circular fire-grate is fixed just 

 within the bottom of the boiler ; and the aperture h, seen in 



