, 1877-05-16

development is agalR rssorted to. 1t is In
this passage from decomposition to %recomposi-
ZION that electricity becomes controllable and
employable By science.
These are totally different properties Of tbs
fluid. The 6rstis in acoofdanoe with the
surface area Of the body on which It is
developed-be it on glass plates. by Eic
ton, or on the metallic plates Of the battery.
where chemical action and heat produce 10.
The larger The surface area exposed the larger
the quantity Of electricity developed, But
while the quantity may be great tbs tension
may be feeble. By tension is meant the energy
Of the effort to escape from the body
ia which the electricity has a%ocunula ed.
Tension increases with tho rapidity Of develop
ment by he activity Of the causes that produce
it.. Thus rapid friction will both develop a
large quantity of electricity 90 a largo glass
plate, and also j. ease the tension Of tbs
electricity developed. But, while the same
energetic friction will not develop a lsrgs
quantity on a small plate, the electric tension
will be increased considerably. In like manner
by tberegular batteries the number of cups will
give electrical quantity without propOrtionato
tension, unless the chemical action of the acids
Oh the metals is stimulated to a high degree,
and rapid combustion Of the sine takes place.
Many substances, chiefly the metals, ore
what are termed good conductors of electricity
that is, when attached to the battery or
developer they conduct the positive and nsgG-
tive fluids thetefrom to the place OF recomposi~
ton. The wires stretched from pole 10 pole of
a telegraph line are the conductors By which tho
electric fluid, developed say 10 New York, il sled TO
Chicago, where il is liberated after performing
is work in moving the sOundar Of the telegraph
instrument. But ii will be noticed that these
wires are suspended from poles. 1t 10 also known
that these poles, especially when wet. are
49, combinations o~1 tbo& I o1HrSo{&r ill ol-.~@
seek the nearest point Of escape from the wire
TO the earth. The earth itself IL a perfect con.
ductor, as it is q great reservoir of latent cleo.
triCity. Why does not the fluid leave the wire
at the first pole and escapes Because 1t 10
attached to the pole by q non.conduCting sub.
stance, over which it cannot pass, and there
fore flies to the next and the next pole, where
the wire is also insulated by a non conductor.
So the fluid must go to where the electrician
has designed to set it free again after It's work
Is done. Now, glass, resin, gutta percha and
such substances are non.conductors, and when
they are ihterpoSed between two conducting
bodies the electric fluid cannot pass them.
Water is q good conductor. When the tele.
graph wires are covered with frozen rain which
coats the wires the insulat0rs and the poles
with an unbroken flament Of ice. the electric
fluid will escape through that medium and the
line will cease to operate until the Toe disap.
pears. AS referred to in a preceding paragraph
the positive and negative fluids at either end
Of the battery or place Of development seek TO
meet again. When the telegraph was 6rat
invented two wires were deemed necessary
one to convey the positive and the second the
negative fluids to the point of decomposition.
But it was discovered that by allowing the
negative fluid to escape at once into the earth
and the positive to pass over its own wire
only one conductor was needed. the earth form
ing the other which completed what Is termed
the "circ1it." 4.4
The volume Of sound emitted by a violin
string is wonderfully increased by the hollow
violin body, with its apertures, placed beneath
it. No matter how rapid the elOngations and
shortening Of the magnetized iron may be, due
to the equally rapid opening and closing Of the
current Of electricity, they are complete 10 each
instance and produce the phenomenon of sound
with equal certainty. By referring back to
the description of the vibrations of sounding
bodies it will be observed that the sounds
produced by longitudinal vibrations In rods
are governed by we'll known laws. The
means Of producing these in the soft iron rod
enclosed by the magnetic coil isi supplied by
the electric impulse. The effect Of tbatuim.
pulse is to cause the rod to- elongats and to
vibrats in doing SO; therefore, whether the