Improvements in or relating to Telephones and the like.
Year: 1899

page_text: Date of Application, 28th June, 1899-Accepted, 29th July, 1899
COMPLETE DI MUITICATION.
Improvements in or relating to Telephones and the like.
RICHARD HAMMERSTEIN, Merchant, of Mülheim on the Ruhr, in the Kingdom
of Prussia, 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:-
This invention relates to telephones and the like and consists in the combination
of a speaking tube or extension with a telephone or microphone, for the purpose
of securing a clearer transmission of sound, such combination being effected by
connecting the tube or extension with the receiver or transmitter containing the
membrane.
In these devices experiments have proved that the extension tube should be
of variable length, corresponding to the distance between the two ends of com-
munication, so as to secure a clear transmission of sound without having to speak
very loudly.
The present invention therefore relates to a tubular extension which can be
shortened or lengthened, so as to correspond with the distance of the two termini
between which conversation is to be carried on.
For this purpose the tube is composed of two or more parts fitting telescopically
within each other, so that the tube can easily be shortened or lengthened. In
transmissions to great distances, say to a distance of about 100 k.m. the small
apparatus i.e. a short tube will not suffice as a rule, and the sound effects must
be increased by increasing the length of the tube, while in connections over a
short distance, a short tube will suffice, a long extension being less effective
especially in the case of strong or loud sounds.
In the accompanying drawings an example of the invention is represented in
Figures 1, 2 and 3.
The tube consists, for instance, of two parts a and sliding telescopically the
one within the other, the tube b sliding within the tube a. The tube a is suitably
connected to the diaphragm holder of the telephone or microphone, while the
tube b, adjustable within the tube a, is provided at its outer end, into which the
user speaks, with a funnel shaped mouth-piece c.
Figure 3 represents the tube in its telescoped form i.c. in its shortest length (l),
in which condition it will serve for short distances, while in Figure 1 the tube is
represented in its greatest length 7. A person using the tube is therefore enabled
to increase, or decrease the length of the tube by drawing the tube more or less
out of the tube a. In experiments made with tubes so constructed it has been
found, when the tube is fully drawn out, that in some cases, when the speaker
is speaking too loudly, a disturbing sound is produced. In order to subdue or
suppress this disturbing sound the apparatus may be provided with means for
regulating the sound in the tube, and consists in an orifice or orifices o at the
inner end of the tube a, and means for covering or uncovering same.
In the accompanying drawings several such orifices o are shown in the tube a,
which orifices can be partly or wholly closed by means of a slide d. When using
the tube for short distances, i.c. using it in the condition as represented in

page_text: Figure 3, the orifices o are covered by the inner end of the inner tube, inasmuch
as this end will pass beyond the orifices o when fully pushed in. If the tube
is used with the tube 6 partly drawn out, the orifices o will be more or less
uncovered, as shown in Figure 2, this position being used when, in consequence
of too loud speaking between short termini, the disturbing noise is observed;
hence at short distances and long distances these orifices act as regulators of the
voice and hence increase the value of the invention. If at such distances it is
found desirable to have the orifices o closed, the slide d is slid over the orifices
which it thus 'covers. From the above it is clear that the slide d can cover the
orifices o wholly or partially, hence it is possible to vary the dimensions of the
open orifices o as desired. The effect of the orifices may be explained by the
fact that the sound waves passing along the tube on to the membrane are allowed
to expand when arriving at the orifices, and hence become somewhat weakened,
preventing thereby the too strong oscillation of the membrane which produces
the disturbing sounds.
The orifices o therefore produce a softening of sounds which may be too
powerful, and render a clear understanding possible, even when the sounds
uttered are too loud. Besides this chief purpose the orifices o in combination
with the slide d also serve as a ventilating device.
When a tube is in frequent use the air within the tube caused by speaking
into it, cannot be changed with sufficient rapidity, to such an extent is this the case
that the effect of the bad air is disagreeably felt on further use of the tube. When
therefore after each conversation is concluded or even during such conversation
the slide d is withdrawn, a rapid renewal of the air inside the tube may be
effected. As has been stated above; the tube as represented in the accompanying
drawings consists of two telescoping parts; but it is, of course, possible that
several such tubes may be arranged to form one tube of adjustable length. The
tube a is preferably cylindrical in shape while the tube 6 may be cylindrical
or gradually contracting towards the mouth-piece. The movable part
may be
fixed in its adjusted positions in any desired manner. In the drawings, Figures 2
and 3, the tube is represented as provided with a longitudinal slit s acting as
a guide for a pint on the inner tube b. The tubes may be made of any material
fitted for the purpose.
The construction as described above may be applied also to rubber or flexible
tubes or the like by combining them with a stiffened or rigid portion which can
be extended or contracted telescopically, by which arrangement the length of
the tube can be modified. The orifices o, with the slide dare placed, in such a
construction, in the portion connecting the tube or the like with the holder of
the membrane or telephone.
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
I claim is:-
1. In telephones or the like a tubular extension of adjustable length for the
purpose of adjusting the length of the tube, substantially as described.
2. In a device of the kind described, an orifice or orifices at the inner end of
the tube with means for covering or uncovering same substantially as described.
3. A telescopic tubular extension for telephones and the like substantially as
described or illustrated in the accompanying drawings.
Dated this 98th Tune 1800
BOULT & WADE,
Agents for the Applicant.