Evening star., 1926-03-28

Potomac Rlver-is it pos
i sible?"
Yes" the interrogation
was assured by Comdr S. G. Hooper,
head of the Radio ana Sound Di-
vision, Bureau of Engineering, United
States Navy; already tests have been
made with some degree Of success"
Comdr. Hooper has been associated
with the development of radio. both
ashore and afloat, for years. and prob
ably Is the foremost authority in the
Navy on the subject OF radio com
munication.
Naval experts predict the undersea
telephone soon will be as satisfactory
as the instrument used in the office
or home. 1t is significant that favor
able reports should be made on expert
ments in developing this latest con-
trivance for transmitting the human
voice simultaneously with observance
of the fiftieth anniversary Of Prof
Alexander Graham Bells great inven-
ton.
At the mouth Of the historic Po-
tomac River floating laboratory
two Naval experimental sound bargeS
carried on experiments in perfecttng
the super-sonic telephone, the scien-
tifc term for the undersea instrument.
This latest phenomenon in communi-
cation is effected by high frequenCies.
Communication by low frequency
sound occurs by echo reflection.
Here the origin of echo is recalled.
In classic mythology Echo was a
nymph-daughter of Earth and Air
who loved Narcissus, and al his death
pined away until nothing remained of
her but a voice, which inherited inn
mortality and wandered about the
world repeating every sound that
1. 1, Ill
echo after the mythical goddess. To
day there are many famous echoes in
the world.
An extraordinary phenomenon. first
discovered by Prof. Paul 'Langeyin at
the Society de Condensation ct dap
pliCations Mecniques. Paris. recently
has been used to telephone through
the waters of the Potomac. Since
Prof. Lanaevin's remarkable disCov-'
cry ractically every nation of the
world has attempted to perfect the
new super-sonic telephone. Under
sea communication is considered so
important 10 safety in navigation
that photographic engineers and
physicists the world over have con-
Quoted experiments.
The remarkable solution of the
problem of communication and of dis
tant signalling which has been found
in the use of the Hertzian waves of
wireless telegraphy or telephony,
which employ them on account of
their ropagation through the etmos
phere above the surface of the land
and that of the ocean, is well known
to all.
THE early results obtained by Prof.
l. Iangevin from his invention
based on the employment of speclai
vibratory waves. called "super-sonlcS,
which transmit themselves through
salt water, were first communicated
70 Washington in the summer OF
1917 in connection with tho anti-sub-
marine problems Of the allied M
tions. Associated with Prof. I9ngeVin
in his invention was Mons. Chiiowsky
Of the Societe de Condensation ct
d'Applications Mecca niques.
However an apparatus for sounding
hy echo has been under trial since
1915 by the Canadian surveying vessel
Cartier, states the international Hy-
geographic Bureau. 1n 1918 the
United States Navy concentrated on
the subject of submarine research by
means of sonic sub-aQueous reflection
and utilized the powerful oscillators
of the Fessenden type.
Briefly, super. .sonics deal with the
sound frequency above 10000 per sec
ond The aDparatus consists OF mosaic
Of quartz CRYSTALS sandwiChed in be-
tween two steel plates and high
voltage current is applied to the in
side plate which causes the crystal TO
eXpand and contract at tho same ire
ouency. The vibration is transmitted
TO the water, setting up elastic or
compression waves which travel in
beam.
The principle is one of direct sound.
This system of a triple plate. quartz
inserted between two plates of steel,
already has been utilized in order TO
establish standards of wave-length.
1t is evident that thus system Is
available which has a definite proper
Oeriod and which, when excited,
reaches a maximum of resonance
when the frequency which eXcites it
is equal to the frequency proper to It,
When efforts are made to deal with
the problem of the working OF an
organ such as the piezo-electric
sandwich in connection with an oscil-
lating electric circuit. in order to
characterize the working Of the
aerial in radio, to introduce the con-
Ception OF the energy which 1t bor'
rows from the oscillating current and
to characterize it by a resistance of
ted are said to constitute energy
derived from the quartz. The appa-
ratus may he compared to a resistance
introduced into the circuit and would
likewise have a certain resistance Of
radiation.
MUCH the same process as that
A'A employed in radio is used for
transmission and receptiOn through
water At least this theory is ad-
vanced for explanation of most types
of the super-sonic device.
For instance a set of valves pro-
duces electrical oscillations in a cir
cult tuned in accord with the fire.
quency of the super-sonfc waves to
he emitted. There is a lamp valve
with three electrodes (triode Valve),
continuous current generator, conden-
ser voltage regulatory. condenser
OF oscillating circuit and a grid-p plate
transformer. This part of the hook-up
is familiar to every radio enthusiast:
The oscilating circuit. fed by the
action of the valve, acts by induction
on another circuit in resonance with
It. Coupled in parallel, this circuit
includes variable oil-condenser to
regulate the frequency and quartz
condenser which allows the electric
oscillations to be transformed into
super sonic waves of the same fire.
quency. The same quartz condenser
receives the super-sonic waves and
transforms them into electrical oscil'
lations in the oscillating circuit. An
amplifier is connected to the termi-
nails of the quartz condenser and the
detection of the Super-sonic echo by
the usual methods OF radio is thereby
oh iV1nd