332 SCIENCE PROGRESS 



bituminous fuel involved two distinct things, namely, the 

 liberation and combustion of the volatile gases in a suitable 

 chamber, and the combustion of the solid coke on the bars of 

 the grate. In one place he described how he proposed to put 

 into practice these principles of fuel combustion, and showed 

 drawings of boiler-furnaces with properly designed and scientific 

 arrangements for providing a secondary and heated air-supply 

 behind the bridge. He was very sarcastic at the expense of 

 inventors, who, even in his day, were patenting devices for 

 " consuming smoke," instead of attempting to show how to 

 prevent its original formation. 



Williams's book was reprinted in 1854 and 1886, but its 

 teaching appears to have had little effect upon the practice of 

 boiler-engineers, who still persisted in designing and erecting 

 boilers with wholly inadequate combustion space for the class 

 of coal that was burned. 



The results of trials carried out by the Manchester Associa- 

 tion for the Prevention of Steam-Boiler Explosions in 1867-68 

 were similarly ignored by boiler-makers and their users, for 

 here again it was proved conclusively that the bituminous fuel 

 of the Wigan coalfields could be burned with high evaporative 

 efficiency and without smoke emission under steam-boilers, if 

 proper attention were given to the design of the furnace, and to 

 the control of the firemen and of the draught. The methods 

 of attaining comparatively smokeless combustion and an evapora- 

 tive efficiency of gl lb. of water per 1 lb. of fuel, in these 

 Wigan trials, were practically those recommended by Williams 

 twenty-nine years earlier, and the chief novelty of Mr. Fletcher's 

 report was the insistance upon the need for good stoking. 

 In his opinion stoking was an art, and should be treated as 

 such, " and not as a slap-dash random process, which any 

 untaught labourer could accomplish." l 



The progress that has occurred during the past fourteen 

 years therefore has been chiefly educational — that is, factory 

 owners, manufacturers, and fuel-users generally, are beginning 

 to accept, and to put into practice, the scientific principles that 

 have been known, but ignored, for so many years. Although 

 a strong case for smoke abatement can be made out on hygienic 

 grounds, it will always be the economic argument that is the 

 most convincing to the man who is actually producing the 

 smoke in his works or factory. Prove to him that a cleaner 

 chimney-top means a smaller coal bill, and he will become an 

 ardent and willing helper in the campaign against black smoke ; 



1 From a paper by J. B. C. Kershaw, read before the Society of Arts, 

 March 20, 1907. 



