162 FERGUSON'S LECTURES. 



LECT. 



^. Historical Account of the Steam Engine. 



Note 48. The invention of the steam engine may justly be 

 considered as the exclusive property of Great Britain, although 

 its potent labours have been productive of the happiest results 

 in nearly every part of the civilized world. But it may be said 

 that steam was employed as a prime mover more than two 

 thousand years ago ; and yet our country, " the first in arts," no 

 less than in arms,, has scarcely possessed this stupendous ma- 

 chine as a mechanical agent more than half a century. To 

 explain this apparent inconsistency, as well as to fill up the 

 very brief sketch furnished by our Author, it may be advisable 

 to examine the engine in its earliest form ; and it will be seen 

 that neither the ingenious philosophical toys of Hero and Bran- 

 cas, nor the more complete apparatus for raising water suggested 

 by Savery and Newcomen, can at all be compared with that 

 chef d'ceuvre of human ingenuity, a modern steam engine. 



The apparatus suggested by Hero, consist- 

 ed of a vessel F, in which steam was gene- 

 rated by the application of external heat. 

 The ball G was supplied with the elastic va- 

 pour thus procured by means of the bent, 

 pipe E B ; a steam-tight joint being provided 

 for that purpose. Two tubes, bent to a right 

 angle at A and D, are the only parts open to 

 the air, and as the steam rushes out from the 

 minute apertures, the re-action produces a 

 rotatory motion. An account of this appara- 

 tus is preserved in Hero's Spiritalia, published by the Jesuits 

 in 1693, and a copy of this highly curious work, with a Latin 

 translation prefixed, is now in the library of the London Insti- 

 tution. 



Brancas's revolving apparatus, as will be seen by reference to 

 the following diagram, was still more simple than that contrived 

 by Hero. A hollow copper ball filled with water, being furnished 

 with a small tube, is seen to give motion to a float-wheel, which 

 is impelled by the action of the elastic vapour generated within. 

 The only work in which a description of this engine has been 

 preserved, was published in 1629. It is exceedingly rare, and 

 the above diagram is accurately copied from an engraving in the 

 possession of Major Colby 



