’ 
PAPIN’S MODEL ENGINES. 383 
The machine in which our countryman was the first to 
combine the elastic force of steam with the property pos- 
sessed by this vapour of annihilating itself by cooling, he 
never made on a large scale. His experiments were 
always made with simple models. The water intended 
to generate the steam was not even contained in a separ- 
ate vessel; enclosed in the cylinder, it rested on the 
metal plate that closed the orifice at the bottom. It was 
this plate that Papin heated directly, to transform the 
water into steam; it was from the same plate that he 
took away the fire when he wished for condensation to 
be effected. Such a proceeding, barely allowable in an 
experiment intended to verify the correctness of a prin- 
ciple, would evidently be still less admissible if the piston 
were required to move with some celerity. Papin, whilst 
saying that success might be attained “ by various con- 
structions easy to imagine,” does not indicate any of them. 
He leaves to his successors both the merit of applying 
his fruitful idea, and that of inventing the details, which 
alone could ensure the success of the machine. 
In our early researches respecting the employment of 
steam, we have had to quote—ancient philosophers of 
Greece and Rome ; one of the most celebrated mechanics 
of the Alexandrian school; a pope; a gentleman of the 
court of Henri IV.; a hydraulist, born in Normandy (in 
that province fruitful in great men, that has enriched 
the national Pleiad with Malherbe, Corneille, Poussin, 
Fontenelle, Laplace, and Fresnel); a member of the 
water in one and the same machine, as an elastic power and as a rapid 
means of forming a vacuum, belonged to Hero. On my side I have 
proved, unanswerably, that the Alexandrian mechanic had never 
thought of steam; that in his apparatus the alternate movement was 
to result only from the dilatation and the condensation of air, arising 
from the intermittent action of the solar rays. 
