The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1896-10-11


cial development of wonderful inven
ton of his which involves nothing les!
than telephoning by means of a ray 0.
light. A few weeks ago L had an ex
tended interview with the inventor re
garding this marvellous instrument, the
substance of which is here given:
Perhaps not single reader OF thi:
article is aware of the fact that nearly
twenty years ago Professor Bell made
the discovery of a method by which h.
might hear a shadow fall. He found in
following up the researches of DR.
Werner Siemens that the rare meta
called selenium possesses the peculiar
quality of varying its electrical conduc-
tivity under the action of light. That
is to say, its resistance 10 the passage
of a current of electricity differs widely
when it is exposed to the light or hid
in the dark.
1t was from this discovery that the
inventor devised an instrument as SIM
pie as its powers were astonishing. He
found that by connecting a cell made
of this metal, selenium, with the ear,
by means of an ordinary telephone, and
then directing upon this cell an inter
ruptem beam of light that it produced
this rare metal was the only one which
possessed this quality of being sonorous,
that is to say of giving out sounds, un-
der the action of light; but in series
! of beautiful experiments Professor Bell
found that all substances possess it
more or less in the same way when
made up in the form of thin discs or
diaphragms. In a word the great in
ventor laid bare for the first time a
new principle of matter.
1t was out of these researches that
the wonderful instrument upon which
Professor Bell is now again at work
| sprang. He gave it originally the name
of the photophone. Put in the broad
est way it aimed to substitute for the
ordinary telegraph or telephone wire a
ray of light. Doubtless there is many
man who would question the sanity
of any one who would claim to be able
to talk for a long distance over q sun
beam. And yet this is exactly what
Professor Bell has succeeded in doing.
The mechanism which he devised does
not differ widely from the telephone in
its general principles, save in the fact
indicated that it substitutes a ray Of
light for the usual copper wire. The il
| lustration which accompanies this ar
ticle gives a very fair idea of its me-
chanical features.
There is first Of all, transmitter
which is made up of a thin diaphragm
of mica or of some other substance, sill
vered at its back so as to make of 1T a
rejecting mirror. The diaphragm is
tube into which the operator talks just
las exactly he would talk into the
transmitter of a telephone.
Against this thin disc or diaphragm is
projected ray of light, preferably sun
light. The light is caught by mirror
and directed through a concentrating
lens whose focus is the transmitting
diaphragm. The latter in turn, re
fleets the ray through second lens,
which again makes the components of
the ray of light parallel, so that it may
travel any distance without dispersion.
At the other station where the receiv-
ing operator is located there is a par
bolic reflector, at the end of which IS
fixed a sile lc:gff cmfwyp ppjj ffififfifh
turn is connected. telephonically, with
the ear. Now when the ray of light
is reflected from the transmitting
diaphragm and the operator speaks INTO
the tube joined with the latter, what
he says may be clearly and distinctly
heard at the other end of the line;
that is at the other end of the travel
ing ray of light. And that, practically
speaking, is all there is to this wonder
full affair
The theory upon which this instru-
ment is built is that the ray of light
may be impressed with sound vibra-
lions in exactly the same way that an
electrically charged wire is impressed
with the sound vibration from the
telephone. When you talk into the lat
ter, what takes place is simply this:
The electrical circuit being brought
into connection with the carbon dia-
phragm, against which your voice
strikes, the wire or current is set in vi
bration, or rather the sound vibrations
or waves are impressed upon the cleo
trical vibrations or waves, just as II
you were to start a series OF rlppleS in
q pond and then add to these a second
series of q different character, which
would follow i'm the same direction but
not the same line of vibration or wave
motion. This, of course, is putting the
matter crudely, but it represents the
notion OF the scientific idea which l
have got into my own mind and which
I hope is sufficiently clear to the read
er.
1t follows from the process here de-
scribed, that if speaking against the
carbon transmitter will set UP such an
agitation in an electrically charged
wire, a mechanism which shall just re
verse the action of the transqnitter will
upon a diaphragm at the other end OF
the line and thus reproduce your
speech.
AS the reader is doubtless aware, all
the trend of modern physical science is /
toward establishing the close relation
ship of the different forms of molecular
motion, which, for the purpose Of dis
tinction, are variously called light,
heat, electricity and sound.
So close, indeed, is this relationship
that Prof. Tyndall, the very highest
authority on the subject, wished to
abolish some of these phrases, notably
that of light" as simply confusing.
And the farther science has gone the
more it has come to see that the only
difference between these varying modes /
of motion the only difference between I
light and heat and electricity and
sound. is the difference of form and /
rapidity. It has found that it is not /
very difficult TO convert the one into /
the other. The conversion of heat or {
electricity into light is so familiar and
a process that we do not
wonder at it at all. But when Prof.
Bell went step farther and demon
strated the possibility Of converting (
light into sound, or at least of causing /
a wave of Tight to produce a wave of (
sound, which is practically tantamount I
to the same thing, he entered into a !
new field and welded a new link in the I
chain of relationship and interdepend- 4
ence You will see that it was but (
step farther than this to his practical /
miracle of telephoning by light.
But to say that this is "telephoning I
by means OF a sunbeam is really a
very crude and Inaccurate description
of what actually takes place. This was
what Prof. Bell discovered by accident +
one day in the course of his expert
ments It CHANGED that he thrust i'm [