71 
Steam Engine, 
the elastic force of the steam is greater than that of air ; 
and if the steam be condensed by the injection of cold wa- 
ter, and a vacuum thus formed, the vessel will be filled from 
the reservoir by the pressure of the atmosphere ; and the 
steam being admitted as before, this water will also be 
forced up ; and so on successively. 
Such is the principle of the first steam-engine, said by 
the English to be invented by the Marquis of Worcester ; 
while the French ascribe it to Papin : though we believe 
the fact is that Brancas, an Italian, applied the force of 
steam ejected from a large eolopile as an impelling po^ver 
for a stamping-engine so early as 1629. The hint so ob- 
scurely exhibited in the marquis of Worcester’s Century 
of Inventions, was carried into effect by captain Savery. 
2. Newcomen’s.— If the steam be admitted into the 
bottom of a hollow cylinder, to which a solid piston is a- 
dapted, the piston will be forced upwards by the differ-^ 
ence between the elastic forces of steam and common air ; 
and the steam being then condensed, the piston will de-^ 
scend by the pressure of the atmosphere^ and so on suc- 
cessively. This is the principie of the steam-engine first 
contrived by Messieurs Nevjcomen and Cawley^ of Dart-, 
mouth. This is soinetimes called the atmospherical en- 
gine, and is commonly a forcing-pump, having its rod 
fixed to one end of a lever, which is worked by the weigh^ 
of the atmosphere upon a piston at the other end, a tem- 
porary vacuum being made below it by suddenly condens- 
ing the steam, that had been admitted into the cylinder in 
which this piston works, by a jet of cold water thrown 
into it, A partial vacuum being tlius made, the weight 
of the atmosphere presses down the piston, and raises the 
other end of the straight lever, together with the water, 
from the well. Then immediately a hole is uncovered in 
the bottom of the cylinder, by which a fresh quantity of 
hot steam ruslies in from a boiler of water below it, u'hich 
