42 Description of the First Steam-Engine, 



by riveting radiating arms inside of them, and making them 

 in other respects strong. 



Mr. Thomas Savery's engines were made, (to use the Mar- 

 quis of Worcester's words,) both to suck and force, as ap- 

 pears from an engraving of Savery's engine in Harris's Lexi- 

 con Technicum, which has what is there called a sucking 

 pipe, as also a forcing pipe. It has two boilers, a larger and 

 smaller one, and two water vessels, there called receivers. 

 The small boiler is supplied with cold water by a branch 

 pipe from the forcing pipe, and the large boiler is supplied 

 with hot water from the small one. The steam, after enter- 

 ing the receivers, is condensed by water falling from a cold 

 water pipe on the outside of the receivers. 



By the Marquis of Worcester's engine not having a suction 

 pipe, the steam in his water vessels is condensed by permit- 

 ting the cold water from the fountain to refill them alternate- 



The great waste of steam in these engines, occasioned by 

 its coming in contact with the surface of the cold water in the 

 receivers, led to the following devices to prevent that waste. 



First, That of introducing a surface of oil upon the wa- 

 ter. 



Secondly, That of introducing a column of air between the 

 steam and the water. 



Third-, That of introducing a floating piston between the 

 steam and the water ; and, 



Lastly, The introduction of steam-tight pistons. 



From what has been stated, it must appear obvious, that 

 the Marquis of Worcester had the honour of being the inven- 

 tor of the steam-engine, and that Mr. Savery had the merit 

 of being the first that brought it to be so far practicably use- 

 ful. But it was to a Mr. Thomas Newcomen that the min- 

 ing interest was first indebted for making it serviceable in the 

 draining of mines. (See Switzer's Hydrostatics.) 



With regard to the experiment of bursting the cannon 

 mentioned in the same article, this will appear quite practica- 

 ble, if we take into account the time that the cannon was kept 

 in the fire, which was much longer than sufficient to have 

 melted it down, had the fire been suitable for that purpose ; it 



