iLconomy of Fuel. 59 



The boiler employed at Messrs. Horrocks's and Co. is very 

 nearly of the same content, and has nearly the same surface of 

 water and flue, as the one used at Messrs. Thomson and Go's., 

 though of different dimensions as to length and width. It 

 will, however, be perceived that the number of cubic feet of 

 water, evaporated in a given time from the former, exceeded 

 the number raised from the iatter in the proportion nearly of 

 two to one. This excess in the power of producing steam, 

 was derived from two causes ; the superiority of the draught 

 of the chimney, and the greater width of the boiler, which 

 permitted a much larger quantity of fuel to be brought into 

 action, and presented a corresponding increase of surface to 

 receive the radiant heat of the fire. It will be likewise seen 

 by comparing experiments, Numbers 9 and 10, that the greatest 

 performance in point of time occurred, without any material 

 reduction in the effect derived from each pound of coal. 



To printing, dyeing, and bleaching works, which require 

 irregular and sudden supplies of steam, a chimney so lofty 

 and capacious as to make the boilers answer the demand upon 

 them with certainty and ease, should be an object of the first 

 importance, since a deficiency of steam is a source on some 

 occasions, not only of delay, but of real injury to the operations 

 there carried on. The utility and economy of such a structure 

 are forcibly illustrated by these experiments; and they also 

 shew that the proportions of the boiler are not unworthy of 

 attention. 



The experiment, N°. 6, at Primrose, was made to deter- 

 mine on what circumstances the saving produced by John Parkes 

 and Sons' method depends. By comparing experiment N°. 6 

 with N°. 7, it will appear that the economy of the plan arises, 

 chiefly, from the perfect combustion of those portions of car- 

 bonaceous and gaseous matter, which commonly escape in an 

 unconsumed and unprofitable state. It is to be observed, 

 that the results of these experiments do not exhibit thp rela- 

 tive strength of the different kinds of coal, but simply the 

 comparative effect of the old and of the now methods of using 

 the same kind of coal under the same boilers. 



