The steam engine familiarly explained and illustrated; with an historical sketch of its invention and progressive improvement; its applications to navigation and railways; with plain maxims for railway speculators. By the Rev. Dionysius Lardner ... With additions and notes by James Renwick ...

46 THE STEAM ENGINE.
activitatis, which is but at such a distance. But this way
hath no bounder if the vessels be strong enough. For I
have taken a piece of whole cannon whereof the end was
burst, and filled it three quarters full of water, stopping and
screwing up the broken end, as also the touch-hole, and
making a constant fire under it; within twenty-four hours,
it burst and made a great crack. So that, having a way to
make my vessels so that they are strengthened by the force
within them, and the one to fill after the other, I have seen
the water run like a constant fountain stream forty feet high.
One vessel of water rarefied by fire driveth up forty of cold
water, and a man that tends the work has but to turn two
cocks; that one vessel of water being consumed, another
begins to force and refill with cold water, and so successively; the fire being tended and kept constant, which the selfsame person may likewise abundantly perform in the interim
between the necessity of turning the said cocks."
These experiments must have been made before the year
1663, in which the " Century of Inventions" was published.
The description of the machine here given, like other descriptions in the same work, was only intended to express
the effects produced, and the physical principle on which
their production depends. It is, however, sufficiently explicit to enable any one conversant with the subsequent contrivance of Savery, to perceive that Lord Worcester must
have contrived a machine containing all that part of Savery's
engine in which the direct force of steam is employed. As
in the above description, the separate boiler or generator of
steam is distinctly mentioned; that the steam fiom this is
conducted into another vessel containing the cold water to
be raised; that this water is raised by the pressure of steam
acting upon its surface; that when one vessel of water has
thus been discharged, the steam acts upon the water contained in another vessel, while the first is being replenished;
and that a continued upward current of water is maintained
by causing the steam to act alternately upon two vessels,