356 lECTURK XXX. 



boratory he was an assistant: it was more convenient than Guericke's, but 

 the vacuum was not so perfect; yet Boyle's numerous and judicious experi- 

 ments gave, to the exhausted receiver of the air pump, the name of the Boy- 

 lean vacuum, by which it was long known in the greatest part of Europe. 

 Hooke's air pump had two barrels, and with some improvements by Hauks- 

 bee, it remained in common use, until the introductiian of Smeaton's pump, 

 which, however, has not wholly superseded it. The theory of pneumatics 

 was also considerably indebted to Hooke's important experiments on the 

 elasticity of the air, which were afterwards confirmed and extended by 

 Mariotte and Amontons,in France, by Hales in this country, and by Richmann 

 at Petersburg. 



About the same time the first steam engine was constructed, by the cele- 

 brated Marquis of Worcester. Hints of the possibility of such a machine had 

 been given a hundred years before, by Matthesius, in a collection of sermons 

 intitled Sarepta, and at a subsequent period by Brunau ; but the Marquis of 

 Worcester professes to have carried the project into full effect, as we are inform*- 

 ed by his account of what he called a fire water work, which is one of his 

 Century of Inventions, first published in 1663, and which is thus described: 

 " I have taken a piece of a whole cannon, whereof the end was burst,and filled it 

 three quarters full of water, stopping and screwing up the broken end, as 

 also the touch hole; and making a constant fire under it, within 24 hours 

 it burst, and made a great crack: so that having a way to make my vessels, 

 so that they are strengthened by the force within them, and the one to fill 

 after the other, I have seen the water nin like a constant fountain stream 

 forty foot high. One vessel of water, rarefied by fire, driveth up forty of 

 cold water ; and a man that tends the work is but to turn two cocks, that 

 one vessel of water being consumed, another begins to force and refill with 

 cold water, and so successively, the fire being tended and kept constant, 

 which the self same person may likewise abundantly perform in the interim 

 between the necessity of turning the said cocks." The machine was, how- 

 ever, not at that time practically introduced, and it was soon forgotten ; 

 Savery's engines were constructed in a manner precisely similar, some time 

 before 1700; and it is uncertain whether he adopted the Marquis of 

 Worcester's ideas, or reinvented a similar machine. About 1/10, the piston 

 4 



