Dr. Fyfe on the Prevention of Smoke, 6fc, 00 



to a certain extent, accomplisli it, but this is not attainable. 

 To shew, however, to what extent the chimney may be lower- 

 ed, I may here mention, that I had an opening made in it a 

 little above where the flues entered it, and then passed an 

 iron plate across, so as to prevent entirely the passage of the 

 gaseous products upwards ; they were of course forced out at 

 the opening, and in this way I have again and again worked 

 the furnace, and during the whole of the time the combus- 

 tion and consequent evaporation went on as before, as was 

 shewn by the engine continuing to do its work, though there 

 was no chimney in use. The method which I have found to 

 answer best in checking the draft, is cooling the products in 

 the chimney ; and the first means of doing this that occurred 

 to me, was to make an opening near the base of the chim- 

 ney, and admit cold air more or less freely, according to cir- 

 cumstances. In the first case in which I had recourse to this, 

 and in which I could not succeed in keeping up steam, when 

 the distributor was in use, from the moment that the cold air 

 was admitted, the steam was easily kept up, and with the con- 

 sumpt of a smaller quantity of fuel than before. There is 

 still another circumstance to be attended toj I mean the mode 

 of firing. It is evident, that if the steam acts in any peculiar 

 way in causing the combustion of the gaseous materials .of 

 the coal, the coal ought to be so thrown on the fire, that these 

 materials should be evolved as near to the distributor as pos- 

 sible ; hence the necessity of pushing forward the ignited 

 fuel, and then throwing the fresh coal as nearly as possible 

 under the distributor, that the gaseous matter discharged by 

 the gradual charring, may be brought under the action of the 

 steam and air by which it is to be consumed. When this is 

 not done, it is not to be expected that the smoke will be pre- 

 vented, far less that there shall be a saving of fuel. 



With proper attention to all of these circumstances, I mean 

 the mode of firing, the due admission of air above the fuel, 

 and the diminution of the draft, 1 believe that in most cases 

 the process will be accompanied with the desired residts. I 

 say in most, for no doubt cases may occur, in which, chieliy 

 from the difficulty of regulating the draft, there may be no 

 saving, but, on the contrary, an increased expenditure. 



