REASON OF MOVING FORCES. 377 



"Well, I must ask, should we dare to refuse the epithet of 

 invention to a proceeding at which the immortal author 

 of the earliest and true principles of statics and hydro- 

 statics would have been astonished ? The apparatus of 

 Solomon de Caus, that metallic envelop in which an 

 almost indefinite motive power is created by the aid of a 

 fagot and a match, will always figure nobly in the his- 

 tory of the steam-engine.* 



It is very doubtful whether Solomon de Caus, or Wor- 

 cester ever had their apparatus made. This honour be- 

 longs to an Englishman,! to Captain Savery. t I compare 



* It has been printed that G. B. Porta had given in his Spiritali, in 

 1606, nine or ten years before the publication of Solomon de Caus's 

 work, the description of a machine intended to raise water by means 

 of the elastic power of steam. I have elsewhere shown that the learned 

 Neapolitan does not speak, either directly or indirectly, of a machine in 

 the passage alluded to; that his aim, that his only aim, was to deter- 

 mine experimentally the relative volumes of water and of steam; that 

 in the small physical apparatus employed for this purpose, according 

 to the very words of the author, the steam could not raise the water 

 more than a few centimetres (some inches); that in the whole descrip- 

 tion of the experiment, there is not a single word implying the idea 

 that Porta knew the power of this agent, and the possibility of apply- 

 ing it to the production of a useful machine. 



Is it thought that I ought to have quoted Porta, at least on account 

 of his researches on the transformation of water into steam? But I 

 should then say that the phenomenon had already been studied with 

 attention by Professor Besson of Orleans, about the middle of the six- 

 teenth century, and that one of the treatises of that mechanic in 1569, 

 contains a special essay on determining the relative volumes of water 

 and steam. 



f Bonnain says that, after Kirch er's death, a model was found in his 

 museum of a machine which that enthusiastic writer had described in 

 1656, and which differed from that of Solomon de Caus only in one re- 

 spect the motive steam was engendered in a vessel totally distinct 

 from that containing the water to be elevated. 



J Thomas Savery was a sailor, but, not being in the Royal Navy, is 

 styled Esquire Savery in the Royal Society correspondence. Nor is 

 our author quite right in supposing this was the first engine. The 



