The Portland daily press. [volume] (Portland, Me.) 1862-1921, 1888-01-13
ELECTRICITY.
MIR. w. "A. Chapman's Lecture IN the
Mechanics Free Course.

Mr.. w. II. Chapman delivered an exceed
inglv interesting lecture last night, at Me-
chanics' Hall, on Electricity and its Prac-
teal Application. The house was crowded
and the audience were highly pleased With
the entertainment. The Lecture WAS most
excellently illustrated with an manner uF
electrical machines and diagrams. THE fol-
lowing is a brief abstrrct OF the lecture
ANY one who is thoroughly familiar with
the science of hydraulics can very easily UNI
darstand electricity. The principles apply
ing TO the conveyance and utilization OF water
p0wer are almost identical with those apply
ing TO electric power. This is an interesting
fact and one that should determine every
mechanic to understand electricity as den-
nitely as he does water or steam power
Everybody is more or less familiar with
the principles OF water power, and may TO
the same extent become familiar with the
principles of electric power, 10y considering
the analogy of the one to the other.
''Water in itself has no power. ! here are
vast oceans of it on this globe, but they DO
no work 1t is the little mountain stream
that turns the mill. Oceans Of electricity are
all about us; everything is full OF it; but 1t
is as dead as the water at the bottom OF the
sea unless stirred into action by some outside
force. The question is frequently asked,
Where does the electricity come from
when you run a dynamo and get electric
lights? Do you draw 1t from the air, or
ground, or where? The answer is, we pump
it. We start with closed circuit Of copper
wire. 1t is just like pipe solid full OF water; ,
we set it moving in one part and 1t has got TO
move in every other part, at the, samel IN
slant. Whatever there is In the dynamo, or
wire, or lamps, is there just the same, whether
it is standing still or in motion. But mo-
ton at the dynamo sets up a circulation
through the whole circuit. and the power OF
the electric current depends on the force OF
the engine that turns the dynamo. Inc
miller's wheel is turned by falling water, but
every drop Of that water had force, previous
ly impaired to it by the suns heat, that took
it from the ocean to the mountain top. 1t
runs back to the ocean and gives up Its pow
er and the miller'S circuit is completed. Like
all other forces, electricity is subject to the
law of conservation of energy. This beau
tiful law, discovered but a few years since,
asserts that the sum OF all the forces in the
universe is a constant quantity. Ii there is
an excess of one kind of force there must be
a corresponding deficiency OF some other
kind of force. One force is obtained only by
the expenditure of some other Ii heat en-
ergy is produced anywhere there must be
disappearance of chemical, mechanical, cleo
trio, or some other force, in exactly equlva-
lent quantity. Ii mechanical force is sought
for there must be an equivalent amount of
heat, electric, chemical, or some other force,
to obtain it. Every force has its fixed value
in the universal market, and horse power is
the medium of exchange on which all values
are expressed. Nature cannot be cheated.
Electricity can only be obtained at Its price.
Electricity is science, and as such is elassi-
fed by certain natural laws. Its whole sum
and substance, as far as known at the pres
ent day, is collected about few simple facts
and laws, the most important of which l
have endeavored to make clear to you this
evening. Bearing these things in mind,
you will be able to see to some extent
why electricity should act as it does, through
the whole range of its usefulness. from the
extreme sensitiyeness of the telephons to the
enormous power Of 10 ton dynamo.