2G ANNUAL OF SCIENTIFIC DISCOVERY. 



"To prevent misapprehension it is as well to state that we have 

 been, for a period of 5 or 6 years, engaged perseveringly in 

 efforts to perfect mechanical stoking, but our first attempts were 

 only partially successful. Our first grate was a modified Juckes ; 

 but we soon found the wear and tear so considerable that we had 

 to turn our attention to discover some means of remedying these 

 very serious defects, and for more than 3 years we were en- 

 gaged in extensive experiments involving much thought and 

 money expenditure. The result is the machine I have the honor 

 to bring under your notice." 



Mr. Lavington E. Fletcher, C.E., said he had witnessed some 

 very carefully conducted trials with this apparatus used against 

 careful hand-firing, and the results were very satisfactory. The 

 chairman said there was no doubt that mechanical stoking must 

 be superior to hand stoking. Such an apparatus as had been 

 described by Mr. Smith was wanted, and it was only a question 

 of cost. Mr. Smith then thanked the chairman and gentlemen 

 for their attention, and said he would be glad to show any gentle- 

 man the furnace at work who would favor Messrs. Vicars with a 

 visit to their works, Seel Street, Liverpool. 



EFFICIENCY OF FURNACES AND MECHANICAL FIRING. 



Having for some time past given a large share of my attention 

 to the subject of the efficiency of furnaces, I have to bring before 

 you a few results of my experience in this most interesting and 

 important inquiry. 



Since the time in which W} T e Williams lived and labored, Pro- 

 fessor Tyndall and Dr. Frankland have shown that the energy of 

 combustion is within wide limits independent of the density of 

 the air, the natural inference at first sight being that in furnaces 

 the temperature of the air does not affect the efficiency. One of 

 V\ r je Williams' well-known experiments was to introduce a bent 

 plate' perforated with 56 half-inch holes into the centre of a fur- 

 nace where one or two bars had been removed for its reception. 

 "Adequate mixture," says Mr. Williams, " was thus instantly 

 obtained, as in the argand gas-burner ; the appearance, as viewed 

 through the sight-holes at the end of the boiler, being even bril- 

 liant, and as if streams of flame instead of streams of air had issued 

 from the numerous orifices. It is needless to add that nowhere 

 could a cooling effect be produced, notwithstanding the great 

 volume of air introduced." 



Now I cannot at present do more than state the simple fact that 

 I have tried similar arrangements in many different instances 

 and under several different conditions, and that I have rarely 

 failed to produce a cooling effect. The arrangement by which 

 the results have been arrived at may be thus described : A few 

 of the ordinary fire-bars are removed from the centre of the flue. 

 A pair of longitudinal bearers about 6 inches apart are then intro- 

 duced, their upper surfaces being level with the common fire- 

 bars. On these bearers are placed small arched transverse bars, 

 each about 1 inch thick, in contact with one another. Semi-circu- 



