JAMES WATT. 29 



of perfection as the principle seems to admit of, afforded the 

 first important exemphfication of the vakie of steam in 

 mechanics. Savery's, the only other practical contrivance which 

 had been proposed, had been found quite inadequate to the 

 raising of water from any considerable depth, its principal 

 power, as we have already remarked, lying, in fact, in the part 

 of it which acted as a sucking-pump, and by which, as such, 

 water could only be raised till its column was of equal weight 

 with a column of the atmosphere of the same base. It was 

 nearly useless, therefore, as an apparatus for pumping up water 

 from mines; the grand object for which a moving force of 

 extraordinary power was at this time in demand. But here 

 Newcomen's engine proved of essential service. Many mines 

 that had long remained unwrought were, immediately after its 

 invention, again rendered accessible, and gradually excavated 

 to great depths ; while others were opened, and their treasures 

 sought after with equal success, which but for its assistance 

 could never have been attempted. It was applied also to 

 various other important purposes. 



Newcomen's engine, however, notwithstanding its usefulness, 

 especially in cases where no other known power could be 

 applied, was still in some respects a very defective contrivance, 

 and by no means adapted to secure the complete command of 

 the energies of steam. The great waste of fuel, in particular, 

 which was still occasioned by the degree to which the cylinder 

 was cooled after every stroke of the piston, from the cold water 

 injected into it, rendered it scarcely any saving of expense to 

 employ this engine in circmnstances where animal power was 

 available. Its whole force, too, the reader will observe, as a 

 moving power, was limited to what could be obtained by 

 atmospheric pressure alone, which, even could the vacuum 



