Daily globe., 1883-08-17

sides being economic, there is no danger
from fire, gas, smoke, or dust incident to
fire. Of course it is not possible for this
device to do away with artificial heating
by means of stoves, furnaces, etc.
The paper elected considerable discus
sion from the members, quite number of
whom had experimental with apparatus
for sun ray heating.
One gentleman asked if the
apparatus would act benefcially
when the room was artifcially heated, and
the professor replied in the affirmative.
THE MAGNEToPHoNE.
The next paper was by Prof. 81. s. Car
hart, upon the magnetophone, or the mod
lfcation of the magnetic field by the rota-
tion of perforated metallic disc.
The experiments of Bell, Preece, Mirca-
der and others on the radiaphone suggest
ed to me the possibility of inte rrupting
or at least periodically modifying the
lines of force proceeding from the poles
of magnet, by means of a
disc of sheet iron, perforated
with series of equdistant
holes and rotated so that the holes should
pass directly in front of the magnetic
pole. It is well known that the armature
placed on the poles of a permanent mag
het diminishes the strength of the external
field of force by furnishing superior ia
cilities for the formation of polarized
chains of particles from pole to
pole. This is the case even when the
armature does not touch the poles, but is
in close proximity to them. If piece of
sheet iron be placed over the poles of
magnet without touching, and magnetic
curves be developed on paper above the
iron they will be found to exhibit less in
tense and less sharply defined magnetic
action than when the sheet iron is re-
moved. If, however, a small hole be
drilled directly over each magnetic pole
the screening action of the sheet iron is
modified in much the same way as when
hole Is made in screen paque to light; for
the developed curves show distinctly the
outline of the holes. If, therefore, the
sheet iron in the form of circular plate,
pierced with number of holes,
be rapidly rotated between the
poles of magnet and
small induction bobbins the action of the
magnet on the core of the bobbins will be
periodically modified because of the pass
ing holes; and hence induced currents will
flow through circuit including the bob
bin. A disc of sheet iron was pierced with
two circles of fquarter inch holes concentric
with the disc, the number of holes in the
two circles being thlrty-two and sixty-four
respectively. On one side of the disc was
placed horse shoe magnet with its poles
very near the rows of holes; on the other
side were arranged two corresponding in
duction bobbins. The circuit was COM
pleted through a telephone and either bob
bin at pleasure. Upon rotating the
disc rapidly, clear musical
sound was produced in the telephone, the
pitch rising with the rapidity of rotation.
Moreover, the bobbin opposite the circle of
sixty-four holes gave the octave above the
other, and each gave a note of the same
pitch as was produced by blowing stream
of air through the corresponding holes.
This paper was also discussed. The
vice president had his theories respecting
the results of the essayist's experiments.
He explained that the theory was exactly
that used in endeavoring to determine the
location of the bullet in President Gar
fields body, which, however, failed to work,
but which, the speaker was certain, should
have worked to an exactness. The theory
is correct, and the reason of its failure was
a mystery.
Prof. Dolber's apparatus not having
arrived, his paper on the static telephone
was postponed until the meeting of the
section in the afternoon.