Pittsburg dispatch. [volume] (Pittsburg [Pa.]) 1880-1923, 1892-04-03

slides. In DAYS of old the power for work
ing pumps was the sheer muscular strength
of men, horses, or oxen. When steam began
to take the place of muscle in this kind oi
drudgery inventors cast about them for some
form of engine in which steam pressure could
be made to act easily and safely. The com.
mon pump provided them with exactly the
model they sought, only that they had to re-
verse its action. Instead of applying power
from without to drive the piston, the piston
with steam behind it became itself driver
to do any work the engineer desired
Reversing the Turbine Wheel
Water has called forth ingenuity in an
other direction. While one class of con-
trivance is in demand to lift and distribute
it, another class is in request when fall or
rapid suggests its use as source of power.
4 generation or so ago water wheels were
Of the overshot and OF the breast models
very wasteful of energy. To-day, except
where a iall of water is so large in volume
that economy is no object, these wheels
have been discarded for turbines, in devils
ing which the inventors of France and
America have led the world. The vanes of
these turbines have been curved with so
much nicely that, practically speaking, the
machines are perfect and unimprovable.
Now, when the work to be done is the old
task of raising water instead of using it as
it falls, the turbine, reversed in its motion,
proves one Of the best water lifters the en-
gineer can employ.
This principle of using machine re-
versedly as we'll as directly has been of i'm
mense service in the progress of invention;
FOR every rule in nature works both ways,
and search, if intelligent and diligent
enough, always discovers how The vanes
OF windmill follow curves exactly suited
for stationary blower or ventilator, and as
in the treatment of air, so in the use of
water. In hydraulic press, pressure, let
us say OF LOCO pounds to the square inch, is
applied through small pump The LIQUID
medium / the apparatus conveys precisely
that pressure per square inch to a piston
which may be square foot or more in area
a Delicate Weighing Machine.
The Emery testing machine reverses this
action. An enormous tension is applied to
an annular brass cushion filled with LIQUID
and corresponding to the large piston of the
hydraulic press by delicate and almost frio
ti,onless mechanism. Its extremely minute
motion under strain is multiplied 400, 900 TO
500. 600 times. At the mandatory of these
machines in Philadelphia is ''rating' ma
chine, employed to keep them strictly to
standard precision. This apparatus will
weigh visiting card, its needle moving
through one-fifth of an inch during the
operation. With a change of adjustment,
which can be effected almost instantly, the
scale will weigh as much as $50 tons
And rules which work both ways have
other applications than those the machine
and engineer can find for them. An inves-
tirator in chemistry or other branch of
science may come upon new process,
which, in its direct working, has wide and
useful applications Reversing it. he may
find il capable of applications more varied
and important still. For every truth has
its converse, and every discovery has but to
l., lacked Mt in reverse to reveal another
In 1890. Oersted, Danish physicist, OBJ
served that straight wire through which
electricity was passing tended to make
compass needle cross it at right angles. In
finding out the converse way in which this
rule works, Faraday made his most brilliant
discovery. He showed that electric cur