Omaha daily bee., 1914-07-28

will be smaller in area than the COM
bined surfaces of the original two, not
withstanding the fact that 1t contains the
same amount of matter. This is so be-
cause the volumes, or total contents,
of bodies vary as the cubes Of their
diameters, while their surfaces vary only
as the squares.
This principle applies to the particles
Of vapor combining to form little drops
in the cloud. II two or three such parti-
cles unite into a single drop each of them
will contribute its charge OF electricity
to the drop, but the surface to be covered
by the united charges will be smaller
than when the particles were separate.
In consequence, the density OF the cleo
trio charge on the combined drop will be
greater than It was on each of the consti-
tuent particles. In other words, the cleo
trio potential will be higher because the
same amount of electricity is now ac-
cumulated on a smaller area.
But when the potential Of an electric
charge is raised it strains. so to speak,
to break away from the surface on which
it is confined and the higher the potential
the greater the strain.
The first drops grow rapidly larger by
attracting others, and every new influx
OF particles brings an inceasing quantity
OF electricity together on continually
diminishing amount of surface This
process alone might produce an electric
potential sufficiently intense to cause
discharge of lightning from a cloud of
high potential to another having a lower
potential. But in preparing the great
phenomena of thunderstorms nature calls
an additional process into play.
As q charged cloud Is driven along by
the wind it acts by induction upon the
surface Of the earth beneath, and the
latter becomes negatively electrified while
the cloud carries a positive charge. Then
the electrified earth reacts inductively
upon the cloud, and so again increases
its potential. In this way the accumula-
ton of electric energy on a thundercloud
may become so enormous that IL bursts
across miles OF intervening air and falls
in thunderbolt upon a tree a rock. a
house, or some other exposed and
prominent object on the earth,
In a dynamo the electricity is generated
by the movement of an electro-magnet
across the lines of force in a magnetic
field. Millions OF such lines curve,
lnNlSlpiet tuIoueu lnt space NnNclOpink
the poles OF every magnet. and when cut
by an electromagnetic moving bodily
among them, they generate a series OF
currents in the coils OF the electro
magnet These currents flow alternately
In opposite directions, but by certain
devices can be combined into a current
passing away from the dynamo in one
direction. The real source of the electri-
cal power of a dynamo is the mechanical
power employed to keep the electro
magnet moving in the magnetic field.
The mechanical energy is changed
into electrical energy by the inductive
effects of the magnetic field Thus
magnetism can generate electricity and
eKctricity can generate magnetism.
Such are the facts; exactly why they
are so no man can yet say.
The current of electricity that flows
from a wet, or dry" battery owes It's
origin 20 a still different cause. Il Is
generated by chemical action. II is
based upon the fact that when two diff