86 
Steam Engine. 
of first displacing the air, and then forming a vacuum by 
condensation. Newcomen was thus enabled to dispense 
with the use of steam of great and dangerous elasticity, to 
work with moderate heats, and to remove at least some 
part of the causes of wasteful and ineffectual condensa- 
tion. To him we are indebted for the introduction of 
the steam cylinder and piston, and for their connection 
with the pump by means of the main lever with its rods 
and chains, to which we might add several other subor- 
dinate contrivances, which do great credit to his ingenu- 
Still, however, the machine required the constant at- 
tendance of a man to open and shut the cocks at the pro- 
per intervals, for the alternate admission of steam and 
cold water : and although traditional report attributes the 
invention of the mechanism by which the engine was 
made to perform this work itself, to the ingenuity of an 
idle boy, we know that the contrivance was first perfected 
by Mr. Henry Beighton, in 1717, who also improved the 
construction of several other parts of the engine. From 
this time to the vear 1764, there seems to have been no 
material improvement in the structure of the engine, 
^vhich still continued to be known by the appellation of 
Newcomen’s, or the atmospheric engine. The boilers, 
however, had been removed from under the cylinder in 
some of the larger engines, and the cylinder had been 
fixed down to a solid basis. Still the steam w^as conden- 
sed in the cylinder ; the hot water w^as expelled by the 
steam ; the piston was pressed down by the weight of 
the atmosphere, and kept tight by being covered with 
water. It was moreover considered as necessary that the 
injection cistern should be placed on high, in order that 
the water might enter wdth great force. It had been 
foiind by experience, that the engine could not be loaded 
with advantage, with more than seven pounds on each 
