Improvements in or relating to Speaking Tubes or Voice Pipes.
Year: 1896

page_text: Date of Application, 11th May, 1896
Complete Specification Left, 11th Mar., 1897-Accepted, 17th Apr., 1897
Improvements in or relating to Speaking Tubes or Voice Pipes.
I, HAHNEMANN ADOLPHUS CUTMORE, of 18 Queen's Road, South Norwood,
in the County of Surrey, England, Engineer, do hereby declare the nature of this
invention to be as follows:-
A well known defect in the use of speaking tubes, especially those that extend a
long distance, is the difficulty experienced in receiving audibly the message
transmitted, owing to the "breaking up" or reverberations of the voice in the
pipe, this causes the mutilation of many words in a sentence, while others are
received quite clear and distinct.
From careful observation and experience I find that this is caused by the
breath emitted in the articulation of some words, entering the pipe, consequently
compressing the air in said pipe and causing percussion, more especially in the
transmission of the voice from noisy stations where it is imperative that the
terminal shall be hermetically sealed, so as to entirely exclude the admission of
extraneous sounds.
To overcome this defect, I form one or more valve or diaphragm covered
apertures in the pipe, so as to counteract the effect caused, by the compression or
reverberations which take place during the transmission of a message.
In carrying out the invention, I make any suitable number of these apertures or
vents in the pipe and over each, seat a diaphragm or suitable flap or other form
of valve. Wheu diaphragms or flap valves are used, I prefer to make them of
coated thin sheet iron, known as sensitized iron, or thin German silver, but any
other suitable substance capable of vibrating easily may be employed.
To prevent any dirt or grit from getting between the diaphragm or valve and
its seating and also to protect it generally, I enclose said diaphragm or valve in a
suitably perforated metal casing.
W. D. ROWLINGSON,
7 Quality Court, Chancery Lane, London, W.C.,
Agent for the Applicant.
I, HAHNEMANN ADOLPHUS CUTMORE, of 18 Queen's Road, South Norwood,
in the County of Surrey, England, Engineer, 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:-
A well known defect in the use of speaking tubes, especially those that extend a
long distance is the difficulty experienced in receiving audibly, the message
transmitted, owing to the "breaking up" of the voice in the pipe; this causes the

page_text: mutilation of many words in a sentence, while others are received quite clear and
distinct.
From careful observation I find that, the breath emitted into the pipe
in the articulation of some words, or in the rapid delivery of a message will
cause this "breaking up" of the voice and my theory is, that this defect is due to
the want of room for expansion for the column of air, as it is disturbed during a
conversation.
The object of my invention is to overcome this defect by providing a suitable
escape or allowance for the expansion of the disturbed air in the pipe as it occurs,
at the same time keeping said pipe intact in so far as its use for conversation is
-concerned.
This I accomplish by placing in the pipe suitable valves of very fine adjustment,
expanding diaphragms, or other contrivance capable of allowing my object to be
fulfilled.
These valves and the like, or what I term "vents" may be of any suitable
shape and construction, and I place a sufficient number of them in the pipe to
obtain the desired result, of course, where a pipe of large diameter is used it
would be necessary to use proportionately large "vents," and for a small pipe,
small "vents."
In the accompanying sheet of explanatory drawings:-
Figure 1, is a sectional view shewing portion of a pipe fitted with a vent in the
form of a flap valve, and
→
Figure 2, shews a free diaphragm or valve as another form of vent.
In carrying out the invention I form a suitable number of apertures such as A
in the voice pipe, and over each place a valve or other suitable contrivance.
I have obtained very good results by using a valve such as is shewn in Figure 1
in which case it is necessary to place two such valves in close proximity but in
opposite directions to each other, so that the disturbed column of air during a
conversation travelling in one direction will act upon one valve and in the opposite
direction on the other; the direction of the voice being indicated by an arrow in
Figure 1.
The valve B I prefer to make of vulcanite or thin German silver, but any other
suitable substance capable of vibrating easily may be employed.
To prevent any dirt or grit from getting between the valve and its seating aud
also to protect it generally I enclose said valve in a suitable metal casing C
having perforations on each side to allow for the egress of the air in the pipe as it
is expanded during a conversation.
The valve shewn in Figure 2 consists of a free diaphragm which is capable of
being moved during a conversation from both ends of the pipe, and would have an
equal effect to the Hap valve before described.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is:
Firstly. In speaking tubes or voice pipes, the vents to allow for the expansion
of the disturbed column of air in the pipe, caused during a conversation, as and
for the purposes herein set forth.
Secondly. In speaking tubes or voice pipes the apertures such as A covered by
a valve B or other suitable contrivance to allow for the expansion of the disturbed
column of air in the pipe caused during a conversation, as and for the purposes
herein set forth.
Dated the 10th day of March 1897
W. D. ROWLINGSON,
7 Quality Court, Chancery Lane, London, W.C.,
Agent for the Applicant.