AND SURFACE CONDENSED 853 



finished here next week, and will try to heat steam in- 

 dependent of water, in small tubes of iron, on its passage 

 from the boiler to the cylinder, and also try cold sides 

 for condensing." In 1829 a simple boiler and con- 

 denser composed of three tubes was made, the inner or 

 fire-tube being 2 feet in diameter and 15 feet long, " for 

 the express purpose of experimenting on the working 

 the same steam and water over and over again j" 1 and 

 on the same subject, " By making the condenser of 

 4-inch copper tubes ^nd of an inch thick, it would 

 stand in one-twentieth part of the space of the boiler:" 2 

 and finally the sketch of the tubular boiler and tubular 

 condenser of 1830, in its boiler portion similar to the 

 best portable boilers of the present day, and the patent 

 specification of 1831. Surely therefore to him belongs 

 the credit of having invented and perfected the tubular 

 boiler and surface condenser 

 Smiles has written : 3 



"For many years previous to this period (1829), ingenious 

 mechanics had been engaged in attempting to solve the pro- 

 blem of the best and most economical boiler for the production 

 of high-pressure steam. Various improvements had been sug- 

 gested and made in the Trevithick boiler, as it was called, from 

 the supposition that Mr. Trevithick was its inventor. But Mr. 

 Oliver Evans, of Pennsylvania, many years before employed the 

 same kind of boiler, and as he did not claim the invention, the 

 probability is that it was in use before his time. The boiler in 

 question was provided with an internal flue, through which the 

 heated air and flames passed, after traversing the length of the 

 under side of the boiler, before entering the chimney. 



" This was the form of boiler adopted by Mr. Stephenson in 

 his Killingworth engine, to which he added the steam-blast with 

 such effect. We cannot do better than here quote the words 



1 See vol. ii., p. 332. 2 See vol. ii., p. 336. 



3 (See *Liii' of George Stcphcnsun,' l>y Smiles, p. 279; published 1857. 



