John Logie Baird (1888-1946)

Television - the problem of seeing at a distance - how near is it?


                         THE SPHERE

[MAY 10, 1924

TELEVISION—The Problem of Seeing at a
         Distance—How Near Is It?

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The Apparatus which Makes it Possible to “See” at
                     Least a Cross by Wireless

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The Radio Vision Transmitter, by which the Inventor, Mr. L. G. Baird, Hopes to
                         Transmit Pictures by Wireless

The problem of seeing by wireless has been
materially advanced by experiments carried
out by Mr. J. L. Baird, a Scottish inventor,
who has actually transmitted a '' cross ” by
wireless. How this has been accomplished
is described in the article below. The possi-
bility of its development in the future offers
a fascinating prospect.

Many people have heard of the work of an
American and a Frenchman in connection
with radio television. But few know that a
Britisher has, by means of apparatus much more
simple than any yet evolved, achieved what may
seem fantastic to the non-scientific mind. He
has seen by wireless.

In order to accomplish this the inventor first
of all chängës light info sound, transmits that
sound by wireless, and then receives the sound
which by a special piece of apparatus is changed
back into light. This is roughly how it is done:
Light waves and wireless waves travel through the
same medium—ether. It is reasonable, therefore,
to expect to find a connecting link between two
things—light and electricity (which produces wire-
less waves). There is a connecting link, and it is
called a silenium cell. The silenium cell is com-
posed of material which gives forth an electric
current varying in intensity according to the
variations of the light thrown upon it.

It may be well to describe roughly the means
by which Mr. Baird has successfully evolved an
apparatus capable of “seeing by wireless.” The
primary power is a powerful light—an arc lamp or
a very strong electric globe. The light from this
is passed through the object to be transmitted.
Let us suppose this to be a cross. The cross then
is cut out of a solid and opaque material. In the
experimental apparatus used the cross was cut out
of a piece of cardboard.

The light which penetrates through the cut-out
image is focussed through a lens on to a silenium
cell. Between the cell and the lens is a disc
which is revolving at a high speed; in this disc
there are a number of holes punched in series of
fives. The first hole is made on the edge of the
disc, the second a little nearer to the centre, the
third a little nearer still, and so on to the fifth
hole, which, is closer to the centre than any. Then
a fresh series starts, and so on around the whole
of the disc.

The effect of revolving this disc in front of the
image is to allow a certain strip of the image to be
transmitted. Thus eventually the whole of the
picture is transmitted in a series of flashes. But
the speed of the disc is so high that the eye is
deceived, and the whole of the image appears to
be sent at once. In front of this disc is another
which is revolved in the opposite direction on
the circumference of this second disc are a number
of spokes so arranged that they cut across the
flashes of light passed through by the holes in the
first disc.

Light and sound are both vibrations, and light
vibrations are extremely fast; sound vibrations are
much slower. The serrated disc allows flashes of
light to pass at a frequency equivalent to a very
high-pitched note. In fact, if a telephone was,
connected across the silenium cell a shrill scream
would be heard. This in reality would be the
“sound of the picture being transmitted by

The light passed by the image is now thrown
on to a silenium cell. This, of course, is after it
has. passed through the two discs, the second of
which has split the light into variations which the
cell can follow. When light is thrown on to a
silenium cell the cell gives out an electric current.
Thus Mr. Baird has made the link between light
and electricity. These electrical impulses, after
being greatly amplified, are passed into an ordinary
wireless or wire transmitter, and thence broad-
casted in the usual manner.

Now as to the receiving end; if wireless is
being employed, the received impulses are again
amplified. They are then passed to the apparatus,
which will make them visible to the human eye.
This is merely a disc upon which there are a
number of “ quick acting ” electric lamps placed
in positions exactly corresponding to the holes
made in the transmitting disc. These lamps are
all connected to a commutator, and to this
commutator the received impulses are passed.

Now the receiving disc is revolved at exactly
the same pace as the transmitting disc. This is
accomplished by methods, with which it is not
necessary to deal at present, known as syn-
chronising. The lamps therefore light up in
“ sympathy ” with the flashes of light passed by
the transmitting disc, and form the original image
which was transmitted,

That briefly is the.apparatus evolved by Mr,
Baird. Eventually, perhaps, the general public
will be able to sit in a kinema theatre, let us say,
or even in their own homes, and see the events of
the day actually enacted before their eyes !


I have just returned from an exciting trip on a
South Afircan whaler, writes a correspondent.
A voyage in one of the tiny vessels is a thrilling
experience, and far more exciting than big-game
hunting ashore. . . .

From the bridge I saw the skipper and mate
at work, preparing the harpoon gun. First a bag
of gunpowder was pushed into the fat barrel from .
the muzzle end; this was followed by
wadding, a rubber disc, and the harpoon,
with its sharp-pointed explosive head
screwed on, the time-fuse set at four
seconds. For hours the chase went
on, the man in the mast-head barrel
following the movements of the whale
under water. The difficult part of the
business is to get in such a position
that a hit is certain; if the harpoon
misses its mark the whale becomes
frightened and will not allow the ship
to get near again.

Scarce had the skipper left the gun
than the whale broke water right ahead.
Back to his post he dashed, throwing
his coffee into the scuppers as he ran.
Then, with his eyes fixed on the light
patch in the water that showed where
the whale was swimming, he waited his_
A grey-blue mass broke surface,
the water streaming from the ridged
backbone. It was a blue whale, eighty
feet if an inch. Then it vanished, and the man
at the masthead continued his chanted instructions
to the wheel. Again the whale rose, but only a
small portion of the huge carcass showed above
the surface, We saw. the backbone arch, and
knew that the whale was sounding. This meant
that it would remain under the surface for ten
minutes at least before coming up to breathe.

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The Vessels which Seek the Whale in South African Waters

These tiny vessels are quite seaworthy, in spite of their size; but life at sea in a vessel
of this type can hardly be surpassed for sheer discomfort. The decks are almost
                                             continuously awash

“ Bla-a-a-ast.” This time It was the man at
the wheel who spotted the whale, away to star-
board. The bows swung round and soon we
were on the trail, following close behind as before.
A spout rose up ahead, so close that the spray
almost fell on the decks. The mass of blubber
was almost under the bows. It was impossible
to miss. Crack! The gunner had fired, and
through the white smoke we saw the
harpoon streak towards the whale and
bury itself in the smooth head, close to
the eye. The explosive head did the rest,
and the great carcass floated dead on
the surface. Carefully the ship ranged
up alongside, men on the forecastle
hauling in the harpoon cable.

The work at the station was in-
tensely interesting. In the morning the
whale ship gleamed in the sun, red with
the blood of two huge blue whales.
Scores of Kaffirs were cutting up the
carcass with flensing knives. The
blubber is quite soft, and peals off in
huge strips like the skin from a banana.
The whole carcass is used nowadays.
First the blubber is removed and boiled
separately. The finest grade oil is
thus obtained. The meat and bones
are boiled as well, and the product ob-
tained after extracting the oil is turned
into fertiliser, rich in nitrogen.