290 OUNNFJIY. 



of carbon, gives 300 millions of duty. If it was applied to the 

 best advantage, say on a piston, calling powder one thousand 

 atmospheres, it would far exceed that duty. A gun 9 feet long 

 and 7-inch bore has 16 feet of cold sides, and condenses at first 

 one-half of its force by its cold sides and loses 150 millions in a 

 200th part of a second, while the ball passes from the breech to 

 the muzzle. This gives 221,760 Ibs. condensed by each foot of 

 surface sides in so short a time. Binner Downs cylinder was 

 taken as condensing 2500 Ibs. for each surface foot in six seconds ; 

 therefore, without taking into account the great difference in 

 time, there is eighty-eight times as much power lost by each 

 foot of cold sides of the gun as by the cylinder sides. This 

 shows what a considerable power is lost by cold sides where the 

 vapour is so rare. Boulton and Watt's engine, doing twenty 

 millions, performs with 1 Ib. of coal a duty of 240,000 Ibs., or 

 about y^th part of what is done by 1 Ib. of carbon in powder. 

 The water evaporated by the boiler is 7 Ibs. thrown into steam 

 by 1 Ib. of coal, and a duty of 33,750 Ibs. for each pound of 

 water evaporated. 



" Suppose 1 Ib. of powder to contain 12 oz. of nitre and 4 oz. of 

 carbon, and ^th part of the nitre to be a fixed water, which would 

 be half an ounce of water in every pound of powder, making 

 the carbon eight times as much as the water ; from this data 

 1 Ib. of water in powder would perform a duty of 28,385,280 Ibs. 



Ibs. 

 1 Ib. of carbon in powder ...... 3,548,160 ) 14 times the consump- 



1 Ib. of coal in Boulton and Watt's engine 240,000 ] tion by the engine. 



1 foot of cold sides of the gun .. .. 221,760 f 88 , tin jf as ^ loss f 

 1 of the cylinder.. 93,160 { %*? 



f 14 times as much coal 



1 Ib. of coal for 7 Ibs. of water in steam . . . . I for water into steam 



1 Ib. of carbon for 8 oz. of water in powder .. .. j as for water in 



' powder. 



" By this it appears that heat is loaded with fourteen times 

 as much water in steam-engines as in powder, and does only 

 T*th part of the duty of the water in powder. It is possible to 

 heat steam independent of water, because if we work with steam 

 of ten atmospheres, it would have ten times the capacity for 

 heat, being in proportion to its gravity. The boiler standing on 



