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ciency. By the attention given to mechanical science by the Earl 
of Stanhope, and above all by the genius of James Watt, the steam 
engine of those ancient days attained a perfection which seemed at 
the beginning of the nineteenth century to be such that there was 
nothing more for man to invent or to aspire to, to increase his 
powers. 
But how does this wonderful invention stand at the present day ? 
The old, simple-acting atmospheric engines, of which I saw some 
remains in my early childhood, have entirely disappeared, except 
perhaps in the museums of mechanical objects. The perfected 
engine of Watt began to be superseded early in the century by the 
invention of Oliver Evans, a citizen of Pennsylvania, who devised 
the high-pressure engine, imperfect in the first place in its structure, 
but wonderful in its effect. Among the examples of his engines, in 
contrast with those of Boulton and Watt, I may be permitted to 
call the attention of this meeting to the two engines which for a 
number of years stood side by side in the building of the Fairmount 
Water Works, which was erected for the purpose of containing the 
engines and supplying the city of Philadelphia with water. There 
was the complicated and ponderous engine of Boulton and Watt, 
with its walking beam and its great fly-wheel, with the improve- 
ments that had been made on the sun and planet movement for the 
accomplishment of the conversion of vertical power into rotary 
power. There was a little engine built by Oliver Evans, occupying 
a space of certainly not more than fifteen feet wide by twenty feet 
long, with its boiler and all its appendages working under a pres- 
sure of 150 pounds to the square inch and performing more work 
than the elaborately constructed and perfected engine of Boulton 
and Watt. 
In this high-pressure engine of Oliver Evans is found the type of 
what are now called the compound steam engines of the present 
day, the steam entering one cylinder at a very high pressure, grad- 
ually emerges from that into a second under a diminished pressure, 
and going on until finally, I believe, it is now passed through at 
least four cylinders, and terminates at the end of its work under the 
pressure with which the Boulton and Watt engines were originally 
worked. 
I do not think too much praise can be given to our mechanical 
inventors. Not only does the steam engine evidence the success 
of their inventive genius and their perfected labors, but the machin- 
