264 CONSTRUCTION OF THE ROCKET." CHAP. XTTT. 



nected. This plan was adopted in the construction of the 

 celebrated " Eocket " engine, the building of which was 

 immediately proceeded with at the Newcastle works. 



The principal circumstances connected with the con- 

 struction of the " Eocket," as described by Eobert Ste- 

 phenson to the author, may be thus briefly stated. The 

 tubular principle was adopted in a more complete man- 

 ner than had yet been attempted. Twenty-five copper 

 tubes, each three inches in diameter, extended from one 

 end of the boiler to the other, the heated air passing 

 through them on its way to the chimney ; and the tubes 

 being surrounded by the water of the boiler, it will be 

 obvious that a large extension of the heating surface was 

 thus effectually secured. The principal difficulty was 

 in fitting the copper tubes within the boiler so as to pre- 

 vent leakage. They were manufactured by a Newcastle 

 coppersmith, and soldered to brass screws which were 

 screwed into the boiler ends, standing out in great 

 knobs. When the tubes were thus fitted, arid the 

 boiler was filled with water, hydraulic pressure was 

 applied ; but the water squirted out at every joint, and 

 the factory floor was soon flooded. Eobert went home 

 in despair ; and in the first moment of grief, he wrote to 

 his father that the whole thing was a failure. By 

 return of post came a letter from his father, telling 

 him that despair was not to be thought of that he 

 must " try again ; " and he suggested a mode of over- 

 coming the difficulty, which his son had already antici- 

 pated and proceeded to adopt. It was, to bore clean 

 holes in the boiler ends, fit in the smooth copper tubes 

 as tightly as possible, solder up, and then raise the 

 steam. This plan succeeded perfectly, the expansion 

 of the copper tubes completely filling up all interstices, 

 and producing a perfectly watertight boiler, capable of 

 withstanding extreme internal pressure. 



The mode of employing the steam-blast for the pur- 

 pose of increasing the draught in the chimney, was also 



