l66 Defcrtpt'lon of a Furnace and 



quoted by the author, give the following proportions *. Equal quantities of heat are produced 

 by the combuftion of , 



403 lbs of cokes "j C 17 of cokes. 



. 600 — ofpitcoal I . f I loofpitcoal. 



£ r u 1 f or in meafure S ,^, , 



coo — or charcoal I 40 of charcoal. 



1089 — of oak J ^ 33 of oak. 



If pitcoal had been uf.d inftead of pine-wood, the number cf pounds of water made to boil hj 

 lib. of the fuel would have been 36,3 inftead of 20,1 ; and as, from the experiments of Watt, 

 it is eftabliflied, that nearly five and a quarter times the quantity of heat is required to con- 

 vert boiling water into fteam as would have raifed the fame water from the freezing to the boiling 

 point, it will follow, that the heat generated in the combuftion of one pound of pit-coal ought 

 to afTord very nearly jibs, of fleam. 



In all the experiments made on a very large fcale, with brew-houfe boilers, rather more than 

 one-half the heat a6tu:;lly produced found its way up the chimney and was loft. 



The fixth chapter of this eftay contains a (hort account of a number of kitchens, public and 

 private, and tire-places for various ufes, which have been conftru£fed under the dire6tion of the 

 author, in different places : of thefe I muft necefTarily forbear to fpeak at prefent. 



Fig. I. Plate VIII. is a front view of the new boiler of the brew-houfe called Neuheufel 

 (belonging to the Eledtor of Bavaria), or rather of its fire-place and cover (the boiler being con- 

 cealed in the brick-work). The infide door of the fire-place is here reprefented fhut; and, in 

 order that it might appear, the outfide door is taken ofF its hinges, and is not fhown. The two 

 vaulted galleries, A, B, in the folid mafs of the brick-work, on the right and left of the fire- 

 place (which were made to fave bricks), ferve for holding fire-wood. The partition walls of 

 the fire-place and the different flues, as alfo a feftion of the boiler, are reprefented by dotted 

 lines. The (mail circular hole on the left of the fire-place door is the glazed window opening 

 into the fire-place, by which the burning fuel may be moft advantageoufly feen, without dif- 

 turbing the current by any opening of doors, a b is the wooden curb of the boiler : c d, 3. 

 platform on which the men ftand when they work in emptying the boiler, &c. : ^y is a plat- 

 form which fervcs as a pafTage from one fide of the boiler to the other. This platform, which 

 is about 18 inches wide, is 12 inches higher than the other platforms, in order that the openings 

 g and h, into the flues, may remain free. Thefe openings, which are opened only occafionally, 

 that is to fay, when the flues want cleaning, are kept clofed by double brick-walls. Thefe walls 

 are exprefled in the following figure. 



Fig. 2. is an horizontal fedion of the fire-place at a level with the bottom of the boiler. «, <?, 

 <j,<7, are four openings, by which the flues, which in the firft arrangement of this fire-place went 

 round the outfide of the boiler, were occafionally cleaned : b is the canal by which the fmoke went 

 off into the chimney. The entrance into the fire-place, and the conical perforation in the wall 



• Thefe experiments, which were communicated to Count Rumford by Mr. Kirwan, are to be found in the 

 Memoirs of the Paris Academy ; I think for the year 1781. 



of 



