442 THE APPLIED SCIENCES, 



struggle, the most menacing and the most dangerous of any in 

 which she has ever been engaged. 



Let us take another example. At the time of the inventions 

 of Watt, the north of England, which supplied by far the greater 

 part of the coal for domestic consumption, and for the arts, had 

 seen all the upper beds of her great mineral treasure exhausted. 

 It was necessary to penetrate to greater depths, in order to supply 

 to Britain a fuel which its forests had long ceased to furnish. 

 But this circumstance greatly increased the cost. The metals, 

 which formed the wealth of whole counties, could no longer be 

 smelted at the same prices as before. The working of the mines 

 thus became more and more disadvantageous ; each year brought 

 a sensible diminution in their produce ; and all the secondary arts, 

 which depended on them for their material, were menaced with 

 decay and ruin. 



The employment of the steam-engine put an end to this down- 

 ward movement, and the whole face of things was altered. A 

 power was obtained, which, with a comparatively small expendi- 

 ture of fuel, lifts an enormous weight from the greatest depths ; 

 and thus renders the expense of raising the coal a very small frac- 

 tion of its cost. The average performance, or (as it is technically 

 called) duty of the Cornish engines, is equivalent to the elevation of 

 fifty-five millions of pounds through a foot in height, by the con- 

 sumption of a single bushel of coal; while that of some of them 

 surpasses eighty millions. And thus it is computed that a weight 

 exceeding one thousand tons is lifted one foot, for the sum of one 

 farthing ! In fact, the economical value of the engine, in mining 

 operations, may be judged from the circumstance that, during 

 the continuance of the patent granted to Watt and Boulton, when 

 they received one-third of the price of the fuel saved, the propietors 

 of a single mine in Cornwall thought it worth while to purchase 

 the right of the inventors for 7500 per annum. 



We have stated that the reduction of the metallic ores was en- 

 tirely dependent upon the supply of coal, and shared its fortune. 

 But the supply of metal was influenced in another, and more direct 

 way, by the steam-engine. The mining engineer was forced, by 

 the feebleness of his mechanical means, to stop at a comparatively 

 moderate depth in the search of mineral treasures. Independently 

 of the labour necessary to lift the ore to the surface, the power re- 

 quired to clear the mine of water soon exceeded any which, previ- 



