IMPROVE- MENTS IN SPEAKING TUBES
Year: 1878

page_text: LETTERS PATENT to Peter William Barlow, of No. 27, Argyle Road, Castle
Hill, near Ealing, in the County of Middlesex, for the Invention of " IMPROVE-
MENTS IN SPEAKING TUBES."
Sealed the 23rd May 1879, and dated the 19th December 1878.
PROVISIONAL SPECIFICATION left by the said Peter William Barlow at the
Office of the Commissioners of Patents on the 19th December 1878.
PETER WILLIAM BARLOW, of No. 27, Argyle Road, Castle Hill, near Ealing, in the
County of Middlesex. IMPROVEMENTS IN SPEAKING TUBES."
"
In speaking tubes employed for communicating from one apartment to another,
as these are ordinarily constructed and used, there is generally a mouthpiece pro-
vided with a whistle plug, which has to be removed for the purpose of speaking
through the tube, and which has to be replaced in the mouthpiece in order to stop
the passage of sound through the tube, and to be ready for attention being called
by the sounding of the whistle. The object of my Invention is to dispense with
the removing and replacing of the plug or whistle by the use of a self acting valve
in conjunction with a fixed whistle, so that the tube is at both ends always ready
for signalling, and is put in condition for speaking or listening by the mere act of
raising the mouthpiece towards the lips or ear of the speaker or listener. For this
purpose I fix a whistle on any convenient part of the speaking tube, communicating
with it by a small aperture or branch pipe. Between the mouthpiece and the end
of the flexible pipe connecting it to the speaking tube I form a lateral cavity, in
which I place a ball, which may be of soft or elastic material, such as caoutchouc,
and is somewhat larger than the aperture at either end of the cavity. When the
mouthpiece hangs downwards this ball seating itself on the aperture acts as a valve,
closing the end of the pipe, and so preventing sound from passing through it, and
at the same time preventing escape of air from the pipe, so that if the pipe be
blown into at the other end the whistle will be sounded. When it is desired to
speak through the pipe, or to listen to speech transmitted through it the mouth-
[Price 6d.1

page_text: piece is raised towards the lips or ear, whereupon the ball drops from its seating
and lies in the cavity at the side of the aperture communicating with the speaking
tube, thus leaving a clear passage between the mouthpiece and the tube. When the
communication is ended, on merely dropping the mouthpiece so that it hangs down-
wards as before, the ball again seats itself, closing the mouth of the tube. It is
advantageous to make the opening to the whistle at the side of the cavity, so that
the ball acts as valve to shut off the whistle when the mouth piece is raised for the
purpose of signalling, speaking, or listening.
Speaking tubes thus fitted may be employed in buildings to communicate from
one room to another, or on shipboard or railway trains to communicate from one
compartment or carriage to another, or in road carriages to communicate between
the passengers and the driver.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Peter William Barlow in the Great Seal Patent Office on the 19th
June 1879.
PETER WILLIAM BARLOW, of 27, Argyle Road, Castle Hill, near Ealing, in the
County of Middlesex. "IMPROVEMENTS IN SPEAKING TUBES."
In speaking tubes employed for communicating from one apartment to another,
as these are ordinarily constructed and used, there is generally a mouthpiece
provided with a whistle plug, which has to be removed for the purpose of speaking
through the tube, and which has to be replaced in the mouthpiece in order to stop
the passage of sound through the tube, and to be ready for attention being called
by the sounding of the whistle. The object of my Invention is to dispense with
the removing and replacing of the plug or whistle by the use of a self acting valve
in conjunction with a fixed whistle, so that the tube is at both ends always ready
for signalling, and is put in condition for speaking or listening by the mere act of
raising the mouthpiece towards the lips or ears of the speaker or listener.
For this purpose I fix a whistle on any convenient part of the speaking tube,
communicating with it by a small aperture or branch pipe. Between the mouth-
piece and the end of the flexible pipe connecting it to the speaking tube I form a
lateral cavity, in which I place a ball, which may be of any suitable material, and
is somewhat larger than the aperture at either end of the cavity.
But to make my Invention better understood I will proceed to describe the same
by reference to the accompanying Drawing, in which Figure 1 is a section of the
mouthpiece and whistle of a speaking tube constructed according to my Invention,
the mouthpiece being in its normal position, that is to say, hanging downwards;
Figure 2 is a section shewing the mouthpiece in its raised position; Figure 3 is a
section of the mouthpiece of a speaking tube constructed according to my Invention,
and suitable for road carriages; Figures 4 and 5, sections of the mouth piece of a
speaking tube as I prefer to construct it when it is required to be furnished with
an indicator, Figure 4 shewing the mouthpiece in its normal or hanging position,
and Figure 5 shewing the mouthpiece in its raised position; Figure 6, section on
line A, B, of Figure 5. Similar letters in all the Figures represent similar
parts.
In Figures 1 and 2 a is the whistle fixed in the aperture of the branch pipe b at
the back part of the mouthpiece c of the speaking tube d; e is the cavity, in which
I place the ball f, which ball is made of any suitable material; g is the opening of
the mouthpiece.
By this construction of speaking tube it will be seen that when the mouthpiece
hangs downwards, as shewn in Figure 1, the ball f will fall by its own gravity
over the aperture of the mouthpiece, closing the end of the tube so as to prevent
sound from passing through it, but leaving the opening to the whistle a free, so that
if the tube be blown into at the other end the whistle will be sounded. When it
is desired to speak through the tube, or to listen to speech transmitted through it,
the mouthpiece c is raised into the position shewn in Figure 2, and placed to the
lips or ear, whereupon the ball ƒ will drop from its seating and will fall into the
cavity e so as to close communication with the whistle a, and leave a clear passago
between the mouthpiece and the tube, as shown in Figure 2.
When the communication is ended on merely dropping the mouthpiece so that it
hangs downwards, as hereinbefore described, the ball f will again fall into its seat
and close the mouthpiece, as shewn in Figure 1.
For road carriages the mouthpiece is formed as shewn in Figure 3, the whistle
being fixed in any suitable position near the head of the driver, the mouthpiece
hanging down in any suitable position near his hand; the mouthpiece at the other
end hanging down in any suitable position in the carriage or vehicle; f is the ball,
and e is the cavity, into which the ball falls when the mouthpiece is raised.

page_text: When several speaking tubes are employed terminating at or near one point it
is the practice to provide each mouthpiece with an indicator to shew which whistle
is sounded. In this case I construct the mouthpiece as shewn in Figures 4, 5,
and 6, the arrangement being very similar to that shewn in Figures 1 and 2, except
that the whistle instead of being placed at the back of the mouth piece, is placed
in the front, and an air chamber h, Figure 6, is provided communicating by the
apertures i, i, with the whistle a. When the tube is blown through from the other
end the whistle will be sounded and the indicator (which being of any suitable
known construction is not shewn in the Drawing) will be forced out so as to shew
which whistle was sounded. On raising the mouthpiece to the ear or lips the
ball will fall into the cavity e at the back so as to leave the tube free, and at the
same time close communication with the whistle a, as shewn in Figure 5. The
raising of the tube by bringing the whistle into the vertical position will also cause
the indicator to fall into its normal position.
Although I have described and shewn in the Drawing a ball as being the most
simple form of valve, yet it will be understood that any other suitable valve may
be employed, such for instance as a hinged valve suitably weighted so as to cause it
to drop into the required position on the raising or release of the mouthpiece.
Having thus described my said Invention and the best means with which I am
acquainted for carrying the same into effect, I wish it to be understood that I do
not confine myself to the precise details herein laid down and shown in the Drawing,
as the same may be varied without departing from the peculiar character of my
Invention, but what I do claim is,―
Firstly. Constructing speaking tubes with a self-acting valve in combination
with a fixed whistle, so that the tube is at both ends always ready for signalling,
and is put in condition for speaking or listening by the mere act of raising the
mouthpiece, as herein before described.
Secondly. The peculiar construction of mouthpiece, as hereinbefore described, and
shewn in Figures 1 and 2 of the accompanying Drawing.
Thirdly. The peculiar construction of mouthpiece for road carriages, as herein-
before described, and shewn in Figure 3 of the accompanying Drawing.
Fourthly. The peculiar construction of mouthpiece for speaking tubes requiring
indicators, as hereinbefore described, and represented in Figures 4, 5, and 6 of the
accompanying Drawing.
In witness whereof, I, the said Peter William Barlow, have hereto set my hand
and seal, this Eighteenth day of June, in the year of our Lord One thousand
eight hundred and seventy nine.
Witness,
G. F. REDFERN,
4, South Street,
Finsbury,
London.
P. W. BARLOW. (L.S.)