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.{ 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. 
Ts 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. 
¢ Bonnain says that, after Kircher’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. 
+ 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 
