The San Francisco call., 1904-02-04
Magnetism.
BY MALCOLM MCDOWELL.
hor Of Shop Talk on the Wonders OF

Radio-activity is a scientific term
Of elastic Interpretation which has been
sadly overworked lately. Whenever
radium. uranium or thorium has been
mentioned. and they all have figured
largely in print recently. it is pretty
certain that "radio-activity' or radio
active" has been used several times.
There has been so much Of the purely
speculative and nOnsensical written
about radium and its astonishing power
Of spontaneously and naturally emit
ting wonderful rays for a time not yet
measured or known, without any ap-
preciable change in the substances,
that the layman who is at all interested
in such things is beginning TO believe
that some scientists. like actresses,
have press agents in their trains.
1t is evident that the earnest, sincere
men who discovered and are expert
menting with and testing the marvel
Gus radioactive bodies are not to be
held responsible for the exaggerations
and wild speculations of uniformed
space filters, for the men whose bril-
liant achievements have startled the
scientific world are extremely conserv-
ative in what they say or write about
themselves. their work and results.
But out Of one of their laboratories
came a few words the other day: 1T
may be that our Investigations may
lead US to the truth about electricity
and magnetism"
Many tinses men have believed they
held the solution of the mystery of cleo
tricity. They have called it a fluid, an
emanatiOn. an emission, a fux, a cur
rent; they have said it was etheric
vibrations, waves of the equally mys-
terious ether; they have thought it TO
be molecular movement or a form of
energy which slid over conductors at
an unthinkable speed. like rubber bands
sliding over a lead pencil They know
its effects: they have learned how 10
handle it and make it do useful work,
but what it is is beyond them.
But when you come to think about ii
magnetism is much more mysterious
tc the ordinary citizen. The average
man has some sort of understandable
idea OF a current of electricity. He at
least can see the sparks and feel the
tingle Of the Juice" but when he OBJ
serves a magnet at work and stops to
figure it out he just naturally gives it
up. He remembers in a hazy way that
when he was a high school scholar ne
learned that electricity and magnetism
were coupled together; that electricity
turned soft iron into magnets and that
magnetism started electric currents.
! When a boy he carried a small horse
shoe magnet in his pocket or magne-
I tized a steel knife blade by rubbing it
with some other boys magnet. There
/ is nothing brilliant or spectacular about
q magnet. 1t exercises its mysterious
power quietly. 1t is this unostentatious
4 characteristic which makes it so inter
esting TO one who looks for the uncom-
mon in common things.
Have YOU ever considered the part
which the magnet plays in your every
! day life?r Did it ever occur to you that
without the magnet ships would not at
tempt to navigate out of sight of land
! for the needle of the compass is a bar
/ magnet2 Do you know how many mag
nets are in daily use in your home?
Every telephone and electric doorbell
has it's magnet Without magnets the
telegraph instruments would be silent,
telephone. exchanges would be closed,
! fire departments would go back to high
watch towers, for there would be no
alarm boxes worth pulling Without
magnets electric street cars would stop
running and electric lights would cease
10 glow, for there would be no dyna-
mos and electric motors.
Railroads would have to go back to
the days before they were paralleled by
telegraph wires, and hotels would be
compelled to return to the wire or cord
pulled bells Of the oId-time inn kind if
magnets should be taken out of the
world. And, of course, all these things
v Vould be if electricity should suddenly
suspend business, for the industrial
magnets are electro o-magnets-pieces of
soft iron, wound around with insulated
wire, 10 be made active magnets when
the electric current circles around the
inert iron through the wire.
Men knew of magnetism and en-
ployed it long before any one ever
| dreamed Of electricity. II is pretty well
established that centuries ago the Chi
rese used the compass-it is believed
they invented it. The ancient Egyp-
tians knew of the power of the load
stone-the dark iron gray mineral found
among some iron ores, to attract iron
to it. The old writer's call the load
stone l6dQlnS SIOnes QUICK IRON ana
'1ovestone." The Chinese have an an
cient tradition of a mountain of mag
netic ore which formed an island and
which drew out the iron bands from
ships that chanced to come within the
limits Of its attraction.
Magnetic chariots or wagons were
used in China as late as the fifteenth
century, and they were the compasses
which enabled Chinese travellers and
armies TO cross great deserts and track
less plains A chariot of this kind car
ried little figure, a manikin, whose
outstretched arm ever pointed to the
south-not the north. as points our
compass needle. A magnetized bar of
steel-probably made magnetic by be-
\ ing rubbed with a ioadstone-was con-
eealed in the pointing arm and was.deI-
icately pivoted. The bar magnet ranged
north and south, but the Chinese put
the index finger on the south end. The
magnetic chariot was drawn in front of
the army, and thus served as a land