MECHANICS AND USEFUL AETS. 51 



NEW TUBULAR BOILER. 



MR. FAIRBAIRN, at the last meeting of the British Association, 

 described a new tubular boiler, which consists of two furnaces, the 

 same as the double-flue boiler, but with this difference, that the cylin- 

 drical flues which contain the grate bars are united at a distance of 

 eight feet from the front of the boiler into a circular flue which forms 

 the mixing chamber, and which terminates in a disc plate, which 

 contains a series of three-inch tubes, eight feet long, and similar to 

 the locomotive boiler. These tubes in a boiler seven feet diameter 

 are 104 to 110 in number, and, from the thinness of the metal, become 

 the absorbents of the surplus heat escaping from the mixing chamber 

 and the furnace. On this principle of rapid conduction, the whole of 

 the heat, excepting only what is necessary to maintain the draught, 

 is transmitted into the boiler, and hence follows the economy of 

 entirely dispensing with brickwork and flues, an important desider- 

 atum in those constructions. 



CORNISH ENGINES. 



THE following statistics of the famous Cornish engines of England, 

 for the months September, October, and November, 1851, are given 

 in Lean's Engine Reporter. These engines, it is well known, are 

 among the most perfect and powerful ever constructed, and the 

 result of their working strikingly illustrates the wonderful precision 

 and magnitude of the steam power. They are employed in raising 

 water from the deep mines of Cornwall. The number of pumping 

 engines employed in September was 21 ; consumption of coal, 1,512 

 tons ; water raised, 13,000,000 tons, ten fathoms high. Average duty 

 of the whole is, therefore, 50,000,000 pounds lifted one foot high by 

 the consumption of 94 Ibs. of coal. 



October, number of engines employed was 20 ; consumption of 

 coal, 1,960 tons; water raised, 16,000,000 tons, ten fathoms high. 

 Average duty, 49,000,000 Ibs., lifted one foot high, by 94 Ibs. of coal. 



November, engines employed was 21; consumption of coal, 

 1,525 tons ; water raised, 13,000,000 tons, ten fathoms high. Average 

 duty, 49,000,000 Ibs., by 94 Ibs. of coal. 



MILLER'S MONOZYMATIC CONDENSER. 



THE object of this condenser is to condense the steam as it passes 

 from the exhaust pipe of the cylinder, by the application of cold 

 water to the outside of the metal, separate from the steam, and to 

 return the condensed steam pure water as feed, to the boiler. 

 The primary object of a condenser is to obtain a vacuum behind the 

 piston, by the sudden reconversion of the steam into water, thereby 

 reducing its bulk. The vacuum obtained in common condensing 

 engines, in good order, is about 13 Ibs. to the square inch, which is 

 just about 2 Ibs. less than the pressure of the atmosphere, and is 



