IMPROVEMENTS IN TELEPHONIC PROVISIONAL SPFICATION
Year: 1882

page_text: LETTERS PATENT to John Edlington Chaster, of Manchester in the County
of Lancaster Electrician for an Invention of "IMPROVEMENTS IN TELEPHONIC
PROVISIONAL SPECIFICATION left by the said John Edlington Chaster at the
Office of the Commissioners of Patents on the 20th July 1882.
JOHN EDLINGTON CHIASTER of Manchester in the County of Lancaster
Electrician "IMPROVEMENTS IN TELEPHONIC APPARATUS
My improvements relate first to the receiving telephone
This I can make entirely of metal except the covering of the wires and in
practice I prefer to make all but the handle and said covering metallic. The
telephone consists of a simple cylindrical box preferably of best soft cast annealed
iron
Through the centre of the end of this cylindrical box passes the soft iron bar
which has upon it a fine thread so that it may be adjusted from the exterior of
the box.
Round this bar I wind the covered wire which forms the coil, or preferably
wind the wire round a thin bobbin so that at any moment the coil can be taken
off and examined. The wire too by the use of this metallic bobbin is more easily
wound. Opposite the end of this central bar I place the diaphragm of ferrotype
iron or other suitable material covering the mouth of the box The whole is then
surmounted with a brass or other cover with the usual hearing orifice. The wires
proceeding from the end of the coil are brought out through the handle. I usually
prefer to fill the telephone to the level of the top of the central core with paraftin
A special point in my telephone is this that the core and box form a single
magnet and the diaphragm being in magnetic connection with the box also forms
part of the magnet being of course the opposite polarity to the central bar and
therefore increasing the action of the telephone.
wax.
This consists of a base
Second With regard to the transmitting telephone
board on which is mounted the usual electric bell, the ordinary shunt motion, the
bell push for ringing the distant bell-the intensity coil when required for long

page_text: circuits, and the binding screws for making the various connections; preferably
hinged to the case or box enclosing these and so as to form a lid, I fix my new
microphonic transmitter. This consists of an ordinary thin board facing the orifice
in the lid: It is suspended by leather or other hinges, and is held to the right slope
parallel with the slope of the lid of the box by a balance weight projecting from a
wire or rod attached to the thin board, upon this board on the side opposite the
orifice I place several say four pair of pillars carrying four pointed carbon rods
weighted with lead wrapped round them, the carbon rods are preferably connected
up in pairs. The whole forms a very neat small apparatus.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Edlington Chaster in the Great Seal Patent Office on the
20th January 1883.
JOHN EDLINGTON CHASTER, of Manchester in the County of Lancaster, Electrician,
"IMPROVEMENTS IN TELEPHONIC APPARATUS
My improvements relate to an instrument for reproducing sounds by the aid of
electricity and magnetism and known as a telephonic receiver.
This telephone hereinafter described is an improvement on the instruments of
Philip Reiss by means of which it is far more delicate in its aptitude for the
reception of minute sounds electrically transmitted, and in order to illustrate my
invention more fully I will narrate the various steps in my discovery beginning
with a description of the telephone of Reiss.
Fig 1. Shows an instrument of the aforesaid Phillip Reiss a, b, is the electro
magnet the coils of which are in an electrical circuit with the electric transmitter
of sound, d is an armature the two ends of which vibrate in front of the two poles
of the electric magnet a b;
To enable it to so vibrate it is suspended by a thin iron suspension bar which
may be considered as a continuation of the armature being firmly attached to one
end of the brass support e in which are inserted the regulating screws to which
latter is attached a spiral spring. The whole is placed on a resonant case h.
My first improvement consisted in removing the armature d, also the support e,
with adjustments f and g.
1 constructed Fig 2, Fig 3, the one pole d of the electro magnetic limb a with
a thin flat continuation d' at right angles so as to overlap the other pole i of the
opposite limb of the same electro magnet a, b;
Behind the electro magnetic limb d the brass support e was placed carrying the
adjustmenting screw f and spiral spring g One end of spring g was fixed to the
support e, and the other end was fixed to the electro magnetic limb d Into this
latter worked the adjusting screw f, by means of which the limb d of the electro
magnet which was made movable through the end of the electro magnet coil a,
could be regulated and thus the distance between the end of the long thin pole d'

page_text: overlaping the end of the pole i of the electro magnet «, b, and the said polo i
could be accurately adjusted.
The next step in my improvement is set forth in Fig 4. which represents an
electro magnet having three limbs consequently three poles two of which were alike
in polarity. The two outside limbs a, c, I made alike in polarity, and the central
limb b of opposite polarity.
The two poles a, c, of like polarity were made like the pole & Fig 3. so that
their ends almost met over the central pole i, Instead of adjusting either of the
two limbs of the outer electro magnets Fig a, c, so that their poles might be
regulated in front of pole i, I preferred to place the spiral spring g containing the
adjusting screw fon to the bottom end behind the central electro magnetic limb b
so that the limb b containing the pole i might be regulated from poles & which
were stationary
Fig 5 is substantially the same as Fig 4 with the coils on the electro magnetic
limbs a, o, removed.
I also constructed electro magnets having more than two limbs the thin poles of
which of like polarity overlapped a central adjustable limb with pole of opposite
polarity as shown in Fig 5 I could thus have 4. 6. or 8. limbs of liko polarity
arranged equi distant from a central limb of opposite polarity.
I now found that the greater the number of limbs of an electro magnet of like
polarity the ends of which project over the central limb of opposite polarity the
greater the effect owing to a concentration of the magnetic field which is required
to exist between the ends of the poles of the electro magnet.
To gain this required advantage I placed the central limb and coil together into
a case of iron which becomes the opposite pole of the electro magnet.
The outer limb Fig 6 of the electro magnet could then be triangular, round,
square, or oval, The pole which projects over the central and opposite pole may
be as in Fig 7. split down the middle or divided into two or more tongues as in
Fig 8, or in separate segments or quadrants as in figures 9.
The adjustment in this electro magnet between the two poles is regulated by
turning one way or the other the central limb which was screwed through the
bottom of the outer and opposite polo
To further strengthen the magnetic field I also constructed the thin pole or poles
of the outer limb of the electro magnet without any slits so that it became a plain
flat surface of great arca compared with the inner and opposite pole
The thin and flat portion of the outer pole which meets over the central and
opposite pole might for the facility of construction be forged, welded, screwed, or
held, tight down on the top of the thicker and outward portion of the electro
magnet.
I found it necessary however that the thin portion of the electro magnet should
be in actual contact with the outer and stronger limb of the electro magnet without
the intervention of any substance whatever thus actually becoming part of the
electro magnet of which it formed one pole.
Having worked out the invention theoretically it now remained to put it into a
simple practical form and Figs 10 and 11 show the latest developement of the
invention In these the current enters by a wire cable w consisting of two
electrical conductors insulated from each other and passing through the centre of
the wooden handle r of the instrument which is made fast to the top inside the
outer pole d. The two ends of the insulated coil around the central coil are.
electrically connected with the ends of the cable proceeding through the bottom of
the handle which are connected with the distant or transmitting station. The thin
portion or top of the outer pole of the electro magnet is protected from injury by
means of a wooden cap screwed down against the outer and thicker portion of
the electro magnet. Where the outer limb of the electro magnet is circular
in form as in Fig 10. Fig 11 the thinner portion of the outer pole may be
held firmly in place as previously described by having the wooden cap which fits
over made with a thin ledge running all round so that when screwed down it will

page_text: tightly hold it so as to become actually a portion of the electro magnet. Through
the centre of the wooden cap v is an orifice directly over the central portion of the
thin pole of the electro magnet by means of which sounds proceeding from the
action of the two poles as will be explained hereafter are conveyed to the ear
with the least possible loss of sound.
It is obvious also that if instruments constructed after the manner of Fig 4,
Fig 5, Fig 6, be placed in wooden cases provided with an orifice directly over the
central magnet the acoustic property of the instrument is greatly increased
Fig 11 represents a form similar to Fig. 10 with the exception that the thin
portion of the outer electro magnetic limb is much larger in area and consequently
more delicate.
The receivers as described and illustrated in Figs 10 and 11 are actuated in tho
following manner.
The current proceeds along the line wire or wires through the flexible cable in
the centre of handler and through the coil on magnetic limb, thus rendering the
whole receiver one electro magnet having an intense magnetic field between the
oue pole of the inner limb and the large area of the outer limb, thus any variations
in the passing current which alters the magnetic field are heard by the molecular
movements of the polar limb of large area
In my Provisional Specification I made mention of a transmitting apparatus, but
though useful I do not desire to claim for such transmitter in this final Specifi-
cation but dedicate it freely to the public and I wish it to be understood that what
I desire to protect and claim is
1st The manufacture or use of telephonic apparatus receiving sounds transmitted
by means of electricity in which one pole of an electro magnet is rendered
sufficiently flexible to vibrate and is attracted by the other pole placed nearly in
contact with its point of greatest vibration, the distanco apart being adjusted by
n screw or equivalent device
2nd The telephonic apparatus substantially as herein described, in which the
line wires come up through the handle and are directly connected to a coil round
a solid core fixed in a soft iron box with thin vibrating lid immediately over the
end of said core, and forming the opposite pole of the electro magnet the distance
between the two poles being accurately adjustable by means of a screw or equivalent
device.
In witness whereof I the said John Edlington Chaster have hereunto set my
hand and seal this seventeenth day of January in the year of our Lord one
thousand eight hundred and eighty three
JOHN E. CHASTER. (L.S.)