Improvements in Sound Signalling and Speaking Tube Apparatus.
Year: 1894

page_text: Date of Application, 13th Jan., 1894-Accepted, 17th Feb., 1894
COMPLETE SPECIFICATION.
Improvements in Sound Signalling and Speaking Tube Apparatus.
I JOHN WILLIAM BLACK, of 71 Commerce Street, Tradeston, Glasgow,
Plumber, do hereby declare the nature of this invention and in what manner
the same is to be performed, to be particularly described and ascertained in and
by the following statement:-
My invention which relates to improvements in sound signalling and speaking
tube apparatus is a development of my prior Patent No. 6195 of 1891.
My present invention has for its object to simplify and cheapen such apparatus.
And in order that my said invention may be properly understood I have hereunto
appended an explanatory sheet of drawings whereon:-
Fig. 1, is a section of one form of the apparatus:
Figs. 2 & 3 are front views of a collapsible chamber.
Figs. 4 & 5, are sectional elevations of modified constructions.
Fig. 6, is a section of a simple form of the apparatus.
Referring to the drawings whereon the same reference letters wherever repeated
indicate the same or similar parts.—
The apparatus shown at Fig. 1, is designed for placing on a table or desk, and
consists of the rubber collapsible chamber a, bell b, tube c, with its flange d',
branch d, with the striker e, in it, and a circular wedge shaped rest or support f
This support has a hole g, made in it and the wire lined speaking tube h, is
preferably screwed into it as shown.
As will be seen the collapsible chamber a, instead of, as in my prior Patent
aforesaid, being enclosed by the bell, is secured on top of and outside it.
The collapsible chamber which is of an inverted conic or nearly conic shape is
made to serve three purposes viz. :-A collapsible chamber, a mouth piece and an
ear piece. In order to make it serve the two latter purposes its base is slit or cut
at i. The elasticity of the rubber causes the sides of the slit to press together and
keep the chamber normally air tight, so that, when the hand is pressed with
sufficient force on the base, the chamber is collapsed and a current of air caused to
travel along the speaking tube h, and sound the bell at the other end. When,
however, it is desired to speak or listen through the chamber it is compressed
laterally or doubled up by the hand, as shown in full lines at Fig. 3, and, as a
consequence, the slit i, is caused to open or broaden out and form an orifice through
which sound waves can freely pass.
As will be seen the bell is secured in place by an internally screwed ring d
which screws on the end of the tube c, and the neck of the collapsible chamber is
expanded over the said ring. The flange eis screwed to the support f.
In the arrangement shown at Fig. 4, a flexible hearing tube is combined with
the apparatus. In this case the tube c, is lengthened and has a downward branch d',
into which the hearing tube j, is inserted:-The ear piece k, which has a ball
valve in it, is secured on the lower end of the tube. K' is a piece of bent wire
brought across the end of the tube so as to prevent the ball 1, passing up it when it
is raised to the ear.
In Fig. 5 the collapsible mouth piece a, is shown as fitted on a hearing tube j.
In this case the mouth piece is made with a tubular extension a¹ which is slipped
over the hearing tube j. Communication is established between the interior of the
tube j, and the interior of the collapsible mouth piece by means of a hole or passage
way m, cut in the wall of said tube. The hearing tube is shown as fitted with a
collapsible chamber n, of the same construction as that described in the Specification

page_text: of my prior Patent aforesaid, at its lower end, but in this case the chamber is
covered with netting o. The chamber n, may, if preferred, be dispensed with.
Fig. 6 shows the apparatus, Fig. 1, as it appears when secured to a wall or
partition. The support f, is not necessary in this case.
Having now particularly described and ascertained the nature of my said inven-
tion and in what mauner the same is to be performed, I declare that what I
consider novel and desire to claim is :-
1. In pneumatic signalling or speaking tube apparatus, a hollow rubber chamber a,
of an inverted conic (or nearly conic) shape, having a slit or cut i, in it, substantially
as and for the purpose hereinbefore set forth.
2. The combination of parts constituting the device substantially as hereinbefore
described and shown at Fig. 1 of the drawings annexed.
3. The combination of parts constituting the device substantially as hereinbefore
described and shown at Fig. 4 of the drawings annexed.
4. The combination of parts constituting the device, substantially as hereinbefore
described and shown at Fig. 5 of the drawings annexed.
5. The combination of parts constituting the device substantially as herein before
described and shown at Fig. 6 of the drawings annexed.
Dated this 12th day of January 1894.
H. D. FITZPATRICK,
70, Wellington Street, Glasgow, Agent.