Steam-Engine — Physics. 157 



PHYSICS, MECHANICS, AND CHEMISTRY. 



Art. XV. On the Revolving Steam-Engine, recently 

 invented by Samuel Morey, and Patented to him on the 

 14th July, 1815, with four Engravings. 



To Professor Silliman. 

 Sir, 



X HE successful emplojTnent of the steam-engine, in navi- 

 gating the rivers and inland waters of the United States, and 

 the probable extension of this mode of conveyance of persons 

 and property, makes those improvements desirable which 

 adapt the steam-engine to this purpose with less complication 

 and expense, placing it .more within reach of individual enter- 

 prise, and rendering it even useful on our small rivers and 

 canals^ 



The steam-engine, though often seen in operation, is not 

 readily understood by an observer, without an acquaintance 

 with the facts in natural philosophy on which its power de- 

 pends : and it may elucidate the subject of this communication 

 to advert, for a moment, to the gradations by which this im- 

 portant machine has attained its present perfection. 



It will be recollected that as early as 1663, the Marquis of 

 Worcester published some obscure hints of a mechanical power 

 derived from the elastic force of steam. 



In 1669, Savary, availing himself of the suggestion, and pur- 

 suing the subject more scientifically, invented his engine, con- 

 sisting of an apparatus to cause a vacuum by the condensation 

 of steam, so that the water to be raised would thereupon, by 

 the external weight of the atmosphere, rise into the chamber 

 of the apparatus, which the steam had occupied. 



As caloric becomes latent in the steam which it forms at 2 12**, of 

 Fahrenheit, and the steam thus formed occupies 1800 times the 

 bulk of the water composing it ; and as it returns instantly tn 



