Improvements in or Connected with Telephones, Speaking Tubes, Stethoscopes, Phonographs, and other Instruments through which Sound Waves Pass.
Year: 1888

page_text: Improvements in or Connected with Telephones, Speaking Tubes,
Stethoscopes, Phonographs, and other Instruments through
which Sound Waves Pass.
I, FREDERICK JOHN SMITH of Trinity College, Oxford, Clerk in Holy Orders, and
Lecturer in the University of Oxford, in Experimental Mechanics, 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, reference
being had to the accompanying drawings, and to the figures and letters marked
thereon:-
The invention has for its object improvements in, or connected with, telephones,
speaking tubes, stethoscopes, phonographs, and other instruments through which sound.
waves pass, with a view to shutting out external sounds, which tend to obscure the
sounds received,, produced, passing through, or transmitted by, such instruments.
In carrying my invention into effect, I apply a flexible fitting to the mouth piece or
transmitter, and to the receiver or ear piece, of such instruments. Such flexible fitting
may consist of a hollow ring of flexible material, preferably of india rubber, which may
be permanently inflated, or which may be furnished with means whereby it may be
inflated and kept inflated, or which may retain and recover its normal shape by its own
elasticity; the said hollow ring is so formed that it may be fitted to the transmitter and
receiver of a telephone, or to the aperture or part of an instrument which receives
the voice or other sound, and to the aperture or part of an instrument which is
listened to.
Being quite soft, the fitting readily adjusts itself to the shape of the ear, mouth, or
other source of sound, thereby making the chamber between the telephone and ear or
mouth, or other source of sound, nearly airtight.
The same appliance, when used as a mouth piece, is made by preference of oval
shape, so as to accommodate itself readily to the shape of the mouth, and said mouth
piece prevents the energy of sound waves being reduced by lateral leakage; when used
in combination with a stethoscope, it is applied to each or either end of it, thereby
securing the advantages before mentioned. The flexible fitting may be constructed
otherwise than as above described.
In the accompanying drawings, Figure 1 is a cross section through a ring mouth or
ear piece, showing it applied to the receiver of a telephone, and Figure 2 is a face view
of the same.
Figure 3 is a cross section and Figure 4 is a face view of an oval or oblong mouth
or ear piece which could be used on a speaking tube.
Figure 5 is a longitudinal section of a stethoscope_showing the application of two
forms of my flexible fitting on the ends thereof, and Figure 6 is a section through one

page_text: end of a stethoscope drawn to a larger scale than Figure 5, showing another method of
fixing my flexible mouth piece thereto.
Figure 7 is a section showing a modification in the construction and method of fixing
my flexible mouth piece, and Figure 8 is a section of a screw valve mouth piece which
may be used with the hollow ring a.
In all the figures like parts are indicated by similar letters of reference.
a is a hollow ring, made preferably of india rubber and provided with a screw valve
mouth piece b, through which the said ring may be inflated, and by means of which it
may be retained in an inflated condition. c is a ring or flange made of the same
material, by which the said hollow ring a is attached to the instrument.
In the construction shown at figures 1 and 2, the ring c is made to grip tightly the
end of the receiver or transmitter of a telephone and so hold the hollow ring a firmly
against the face of the same. If desired the said ring c may be fixed in position by
cement or other means.
In the construction shown at Figures 3 and 4, the ring a is made with a ring c
of conical or inclined form, so as to grip tightly the terminal fitting of a speaking tube.
In the stethoscope represented at Figure 5 one end of the stethoscope is fitted with
a hollow ring a of half round section cemented on to the end thereof, and such hollow
ring a is represented as provided with a screw valve mouth piece. b, by which the same
may be inflated and kept inflated; the other end of the stethoscope is represented as
provided with a hollow ring a of circular section provided with a ring c which is
cemented into a circular groove in the end of the stethoscope. In this latter case the.
hollow ring a may be provided with a screw valve mouth piece b, by which it may be
inflated, or it may be permanently inflated and used without such mouth piece b.
In the construction shown at figure 6, the hollow ring a is shown provided with a
flange c which is fixed to the end of the stethoscope by means of a ring d screwed
thereto.
In the construction shown at figure 7, the flexible fitting consists of a hollow ring a
of approximately horse shoe section cemented or otherwise fixed to a projecting rim
formed on the receiver or transmitter of a telephone, or to the terminal fitting or
fittings of other instruments of the character herein referred to. In this case the
flexible fitting or ring a would retain and recover its normal shape by its own
elasticity.
The hollow ring a may also be made of animal or vegetable tissue distended by
inflation, or by being packed with elastic material, such as pine wool or felt, or a soft
elastic ring a may be otherwise formed.
It will be seen from the above that my flexible fitting for the terminal apertures or
fittings of various instruments of the character referred to, may be provided with
means for inflating the same, or may be used without such appliance, and they may be
fixed to the terminal apertures or fittings in any convenient manner.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
1 claim is
The application of a flexible fitting to the mouth piece or transmitter and to the ear
piece or receiver, or to the terminal apertures or fittings, of telephones, speaking
tubes, stethoscopes, phonographs, and other instruments through which sound waves
pass, substantially as herein shown and described and for the purpose stated.
Dated this 21st Ja
1