The Princeton union., 1893-04-06
SCIENCE AND INDUSTRY.
INTERESTING SUBJECTS FOR
CURIOUS READERS.
a Process for Obtaining Electricity
Directfron Heat--The Electric d
Currents of the Skin--High
Speed Railroad Re-
cords Broken. t8

4
Speed Railroad Re-
cords Broken.
q Process Tor Obtaining Electricity !
Direct From Heat.
Berliner has contlived process for
obtaining electricity directly from heat,
basad on the theory that the inductive
capacity of magnetic metals is reduced
by heat and becomes zero at certain
high. temperature. If, then, the metal
is cooled below this high temperature,
It's inductive capacity increases slowly
until ii reaches it's maximum. Mr.. Ber~
liner utilizes this principle by alternate
ly heating and cooling a mass of metal
within magnetic field, and he makes
use of the vibrations Of the inductive
capacity of the magnet thus produced
for the generation of the electrical i'm
pulses. The apparatus by which the
electricity is generated consists prac-
hcally of a big telephone with it's
mOuthpiece over a hot fire. The mag
net, is, however, a hollow cylinder,
while the part that corresponds with
the mouthpiece is an armature OF iron
mounted in Il ring of brass, and this
is supported in the brick walls of the
furnace. AS in the telephone, coil Of
wire surrounds the end of the magnet,
I just above the armature previously al
luded to. AS soon as the fire is started
in the furnace, the armature will be
heated to a bright red. In this condi-
ton it loses the greater part OF it's in
+ ductive capacity, and, according to
well known law of magnetO-electrlc IN
duction, Il current of electricity is thus
generated in the coil. Practically the
effect of slowly heating the armature
is the same as if it were slowly re-
moved from the magnet. Now, If
through the cylindrical magnet cur
rent of cold air or few drops Of cold
water are thrown upon the hot arIna-
ture, it, will be cooled instantly. This,
will have the same effect upon the coil
of wire as if the armature had been
suddenly brought near the pole OF the
magnet, and strong current OF cleo
tlicity will thus be generated. AS soon,
however, as the armature becomes
heated again. another electrical impulse
is sent through the coil, and still an
other when the armature is then cooled
1t will thus be perceived that by al
ternately heating and cooling the az
mature, series of alternating mag
"a neto-electric impulses is generated,
which. can be made to succeed each
other with considerable rapidity. This
is, of course, an experiment which at
present is of scientific value only.
Electric Motors for Farmers Use.
Can this be made an actual and prac-
tical fact? 1t is true that for some
. years electrical engineers have been
at work to devise a feasible plan for
using this power on farms and on cou1l-
try roads, but the limitations have been
so many, and the old prejudice against
any new invention so great, that thus
far the hope has not really ripenetl
into q practical fact.
Essential to the success of this plan
in any neighborhood is the condition
that there should be an abundance
of coal or Of water head, and resi-
dents enough to make the cost of the
plant per capita not too large. In any
suburban neighborhood Oh in localitie:
where garden truck and small crop.
are produced, the electrical experts are
convinced that their plan, which il
the use Of electricity as a power tt
supplant horses, could be economical!
put into practice.
is a waste every year through the TIM
lost in transportation over cOuntr!
. roads, with delays and breakage O
gear, and the cost OF the millions o
. horses and wagons required, and lik
waste of power in other work about tn
farm, which, if saved, would be NOR
than enough to pay the amount o
taxes of whatsoever nature borne b.
the farmers On every farm enough
horses have to be kept the year roun'
u to do the work at the busiest seasons
This means that for a few weeks o
activity animals must be fed and care
for the entire year. The corn, oats an
hay which a horse eats in one mont
would buy enough coal in most part
of the country to furnish more powe
than the work of the animal in yea
How all this may smack someWha
of the impossible, but when we rea
ize how frequently invention has a.
complished the impossibility, it woul
seem that the utilization Of electricit!
as motive power in all the detail {
farm work, would ere long be as
assured fact as the use of electriclt
to move railway cars, sewing machine
or in any of the many other Of its al
plications to practical uses
ElectrO-Denttstry.
An authority in dentistry has calle
attention to very important requir
ment connected with the ,increasir
use Of electricity by dentists He, poin
out the ,lamentable results which hay
SO often followed on the application
q electricity by medical men who a
POORLY equipped with electrical know
edge, and urges dentists not to pla'
themselves i'll Il similarly false positio
I but, at all events, to master the el
mentary principles of electrical scienc
Il Ele also gives some facts, Lot general
known, which have been deduced fro
histown experience. He has found tn
it takes twenty times more pressure
overcome the resistance in the too
than in the soft tissue. The cOndu
H tivity is also modified by age, temper
ment and the nature of the diseas
Hence, greater quantity is used