62 Dr Fyfe, on the Fremntlon of Smok^, 4-<?, 



In giving the above as the increased amount of evapora- 

 tion, and consequent saving in fuel, by the use of steam, 1 

 wish it to be understood, that the remark applies solely to 

 tlie results of the trials above recorded. It is not to be ex- 

 pected that the same is to be got in all cases ; indeed, it has 

 been the reverse, for I must ov^n, that in many cases, in 

 wliich the distributor has been used, there has been no saving 

 in fuel, nay, in several there has actually been a waste ; more 

 coal having been consumed in the same time to keep up the 

 same amount of evaporation. Now, as it must be admitted, 

 that what has been done with one furnace, should, under pro- 

 per management, be done with others, it becomes of import- 

 ance to ascertain what is the cause of failure in these parti- 

 cular cases. In order to discover this, it is necessary to at- 

 tend to the different circumstances accompanying the action 

 of the steam ; and first, after the furnace is brought into good 

 condition, from the moment that the steam is projected into 

 tlie furnace, the passage of air into the ash-pit, and from it 

 up through the fuel, almost entirely ceases, provided air be 

 admitted by the door ; indeed the combustion may be carried 

 on with the ash-pit quite closed, and hence the absolute ne- 

 cessity of admitting air by the furnace-door, or otherwise, so 

 that it shall be brought into contact with the fuel, and also 

 with the gaseous inflammable matter evolved from it. The 

 want of due attention to this circumstance has frequently 

 caused a failure, not only as to the economy of fuel, but also 

 as to the prevention of smoke ; the deficiency in the supply of 

 air causing the gaseous inflammables to escape, without being 

 entirely consumed. Again, by the admission of steam, the 

 draft is very much increased ; indeed so much so, that where 

 the chimney is tall, and consequently the draft originally is 

 great, it becomes so greatly increased, that the heat gene- 

 rated by the combustion is hurried off, and time is not given 

 for the water to take it up. It may naturally be supposed, 

 that by lowering the damper, as Ls usually done, the exces- 

 sive draft would be checked ; but this is not the case, the posi- 

 tion of the damper having little or no effect in altering the 

 draft. I had recourse to several methods to obviate this dis- 

 advantage. The lowering of the chimney no doubt would. 



