The Princeton union. [volume] (Princeton, Minn.) 1876-1976, 1894-02-08
< TORPEDO TELL-T4LE.
The Hyt1rophone Registers the Move
ment ofsAny Craft Within q Mile.

The HySlrOpl ON g Reg1stefs the Move
ment of.Any Craft Within Mile.
Experiments are now being conducted
on the perfection of the hydrophone,
which promises to be Of great value in
marine warfare. The principal object
Of this simple apparatus is to give
warming to a port or fleet Of the ap-
proach Of a torpedo boat, even if the
latter is totally submerged, and. there
fore, quite invisible. IT. consists es-
sentially Of two parts. one submerged
in the sea at Il proper distance from the
port Of fleet to be warned, and at q
depth sufficient to escape the surface
agitation. This part may be described
as an iron bell jar, which, on being
plunged mouth downward into the wa
ter. retains a volume of air in the up
per portion OF bottom. where a copper
box, protecting the sensitive organ Of
the apparatus is fixed.
The organ, in question is merely
very delicate vibratory contact, which
makes and breaks an electric circuit
connecting the submerged bell with the
Indicator or second part of the hydro
phone, situated on shore or on board
one Of the ships of the fleet. The con-
tact is formed by fiat horizontal
spring fixed at one end and loaded
at the other by 4 heavy piece of brass,
having on it's upper surface Il small
platinum stud. A fine platinum needle
kept upright by a vertical guide rests
its lower end loosely on the platinum
stud. The needle and the stud are
connected in the electric circuit through
the guide and spring, and when the
needle dances on the stud the circuit
is made and broken. An electric cur
rent from the ship or shore battery
is always flowing through the circuit
that is to say, between the submerged
bell and the Indicator. Now. the pro-
peller of torpedo boat or Of a torpedo
sets up vibrations in the water, and
these, reaching the submerged bell,
agitate the trembling contact, SO that
the needle dances on the stud and inter-
that the indicator begins to work and
announces the submarine disturbance.
This part of the hydrophone consists
essentially of an electromagnetic,
through which the current passes, with
an armature free to OSciliate when the
current is rapidly made and broken
that is to say, when the current be-
comes intermittent. The motion Of
this armature can be seen by an observ-
er if he chooses to watch. but actual
observation is not required, for the
Indicator itself gives the alarm. This
takes place when the swing Of the ar
mature carries it within the attraction
of a magnetic contact piece fixed near
it. The armature is then drawn to
the contact piece and held fast there.
The swinging armature and the contact
piece are connected in the circuit Of
a local battery. and when they meet
the current flows to ring an electric bell
or light an electric lamp. The tor
pedo boat thus announces its own ar
rival on the scene in spite Of itself,
and precautions can be taken against
it.
The hydrophone is at present under
going practical trial in the Solent,
and Capt. McEvoy, the inventor, es-
Inmates that three of the instruments
suitably placed would be sufficient to
! protect Portsmouth harbor. He is now
engaged in constructing a larger bell
than that already submerged, in order
to meet the requirements Of the govern
ment authorities. The apparatus is
beautifully worked cut and compare
lively inexpensive Moreover, it is sui
ficiently sensitive to announce the pass
age Of steamers mile distant from the
bell. Obviously, such an instrument
might also be used for submarine sig
mailing, for Ship by stopping and start
ing her propeller, could send a message
In the Morse code. and the shore could
respond by flashing an electric lamp.
Ir the case Of another ship the response
might be made by her propeller.-Lon'
don Times.