Victory of the " Rocket " Locomotive 



of steam which the boiler can generate, and 

 upon its degree of elasticity when produced. 

 The quantity of steam so generated, it will be 

 obvious, must chiefly depend upon the quantity 

 of fuel consumed in the f nace, and, by neces- 

 sary consequence, upon the high rate of tempera- 

 ture maintained there. 



It will be remembered that in Stephenson's 

 first Killingworth engines he invited and applied 

 the ingenious method of stimulating combustion 

 in the furnace by throwing the waste steam into 

 the chimney after performing its office in the 

 cylinders, thereby accelerating the ascent of the 

 current of air, greatly increasing the draught, 

 and consequently the temperature of the fire. 

 This plan was adopted by him, as we have seen, 

 as early as 1815, and it was so successful that he 

 himself attributed to it the greater economy of 

 the locomotive as compared v vith horse-power. 

 Hence the continuance of iti use upon the Kil- 

 lingworth Railway. 



Though the adoption of the steam blast greatly 

 quickened combustion and contributed to the 

 rapid production of high-pressure steam, the 

 limited amount of heating surface presented to 

 the fire was still felt to be an obstacle to the com- 

 plete success of the locomotive engine. Mr. 

 Stephenson endeavoured to overcome this by 

 lengthening the boilers and increasing the sur- 

 face presented by the flue-tubes. The "Lanca- 

 shire Witch, " which he built for the Bolton and 

 Leigh Railway, and used in forming the Liver- 

 169 



