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MEGASS AS FUEL.Relation between Cane ground and Requisite HeatingSurface, etc.—The writer has had access to essential data on these pointsas they occur in a large number o£ well equipped modern factories and as aresult has concluded that no average datum can be given, the variation infactories, all of which were working well, being so great. In the followingtable ' cane ' means the short tons of cane ground in 24 hours; 12 square feetheating surface in a smoke tube and 10 in a water tube are taken as the equivalentof one horse power; all surfaces are expressed in square feet: —Eatio of Maximum. Minimum.Horse power to Cane 2.4:1..................... .98 : 1Heating surface to Cane 24 : 1.................... 12 : 1Grate surface to Cane 1 : 3.0................... 1 : 14.6Grate surface to heating surface 1 : 54.................... 1 : 343FIG. 222.As shown in greater detail in another section, the thermal value of a poundof megass of fixed water content is sensibly constant, and hence it wouldappear reasonable that a fairly constant ratio of heating surface in boilers andhence of horse power would obtain; actually, the smallest variation in thisratio does obtain and the writer thinks that a ratio of heating surface to caneof 18 : 1 is ample and representative of good modern practice.On the other hand, however, there is no reason for expecting anyuniformity in the ratio between grate area and heating surface; this will ofcourse depend on the intensity of draught, a smaller grate area being sufficienttinder forced or induced draught than under natural draught.As will be explained in greater detail in a subsequent section, the weight of acubic foot of megass from varieties (or even in different seasons from the same409