IMPROVEMENTS IN FLEXIBLE. ELECTRIC CON- DUCTORS AND TIPS THEREFOR
Year: 1878

page_text: LETTERS PATENT to George Jolin Stanford, of No. 9, Southampton Buildings,
London, for the Invention of "IMPROVEMENTS IN FLEXIBLE. ELECTRIC CON-
DUCTORS AND TIPS THEREFOR." A communication from abroad by Eugene
Francis Phillips, of the City and County of Providence, State of Rhode Island,
United States of North America.
Sealed the 4th March 1879, and dated the 12th September 1878.
COMPLETE SPECIFICATION filed by the said George John Stanford at the
* IMPROVE-
Office of the Commissioners of Patents on the 12th September 1878.
GEORGE JOHN STANFORD, of No. 9, Southampton Buildings, London.
MENTS IN FLEXIBLE ELECTRIC CONDUCTORS AND TIPS THEREFOR."
cation from abroad by Eugene Francis Phillips, of the City and County of Providence,
State of Rhode Island, United States of North America.
A communi-
The electric conductors, sometimes called electric cords, to which my improve-
ments relate, belong to that class which are necessarily flexible for convenience in
use with telephones, telegraphic switch boards, electro-therapentic apparatus, as well
as in other similar connections. These conductors are usually enclosed in one or
more braided or woven jackets for purposes of insulating and strengthening, and
they are provided with solid tip wires for attaining a detachable electric connection
with screw posts wherever used. Usually, the electric wires of these conductors
are very small, and they are composed of fine soft copper having but little tensile
strength, and it is therefore important that the jacketing be so arranged with
reference to the tip wires that the conducting wires cannot be subjected to undue
tensile strain, and one portion of my improvements has special reference to attaining
this end. It is also very important that a good electric contact be attained between
the tip wires and the electric conductors, and another portion of my improvement
has special reference thereto...
It is also important, especially with telephone conductors, that they should be
strong and neat in finish, and one. portion of my improvement relates thereto, and

page_text: another portion of my improvement relates to a telephone conductor arranged for
use with a pair of telephones.
Referring to the Drawings herewith. Fig. 1 represents a complex flexible con-
ductor complete for use, with a pair of telephones, so that a person receiving a
communication may apply one to each ear.
Fig. 2 represents the three insulated wires or sets of wires contained in the con-
ductor, Fig. 1.
Fig. 3 represents one of the ends of the conductor, and illustrates mode of
applying the finishing or outer jacket.
Fig. 4 is a central longitudinal section of one of the improved tips as applied to
the end of a flexible insulated electric conductor, with the conducting wire and tip
wire shown in elevation, and the latter in two positions, the solid lines showing it
just started through the forward end of the shell, and the dotted lines showing it in
position longitudinally, to be fastened in place by crimping the shell.
Fig. 5 is a view similar to Fig. 4, but showing the tip wire and conductor secured
permanently in place by the crimping of the shell.
Fig. 6 is a side elevation of the shell and needle disconnected.
Figs. 7, 8, and 9, are similar views, shewing modifications of the tip wire, and
Fig. 10, a similar view showing a modification of the mode of crimping the tip
wire in place:
The electric wires a and b, Fig. 2, are for connection with the ground and line
wires. The wires d constitute an independent cross cut conductor. These several
wires or sets of wires are insulated electrically from each other by suitable jacketing,
and are all embraced within one cord, constituting a complex conductor, as in
Fig. 1, which has at one end two branches a' and 6' for connection with screw
posts of the line and ground wires, and at the other end four branches, of which d¹
and a² are for connection with the screw posts of the magnet of one telephone, and
d² and b² are for connection in like manner with another telephone. The branches
d' and d² must of course be connected with opposite poles, so that the electric
connection will be perfect along conductors a through one magnet, thence along the
cross cut conductor d to the magnet of the other telephone through said magnet,
and thence back on conductor b.
It will be seen that there are four junctions of these branches. The main junction
being at c, where the ground and line wires separate and join with the cross cut
conductor. The junction c³ is that at which the line and ground wires separate
from the main cord for convenient separate connection with screw posts. The
junctions c' are where the cross cut wire branches from the lines and from the
ground wires. To attain a strong neat finish at these junctions is very desirable,
and is attained in such a manner that the exterior covering is one continuous
tubular fabric extending from the end of one of the branches at one end to the end
of one of the branches at the opposite end of the complex cord. This is done as
follows: The several elastic conductors are first suitably insulated preferably with
fibrous material wound or braided, and sometimes treated with insulating matter,
commencing for instance, on the conductor a at a, its outside jacket is braided to a
point beyond its junction with the cross cut conductor at c¹, and then it is cut free
from the braiding machine, and connected by a winding twine to conductor d.
The conductor & from d¹ is then covered down to the junction c¹; the previously
covered end is then passed upward through the strands in the machine, and the
braiding operation continued, (preferably with a slower feed) upon both conductors
to the point at which they are to merge with the main body of the cord at junction
c, the free end of the cross cut conductor is then lifted through the strands, and
after passing said junction, say, for an inch or so, the braiding is cut from the
machine. Next, at the opposite end of the main cord, one of its ends, as for
instance, that at b', 'is then covered to a point beyond its junction with the main
cord at c², and then cut from the machine:-Now, returning to the uncovered
branch at the opposite end, one conductor, as for instance that at 62, is covered
beyond the point of junction with wire d at c', and cut from the machine, after

page_text: which the wire d is covered downward from its end d³ to the point of junction at
c¹, the previously covered end is then passed upward through the strands, and the
braiding continued down to the main junction c, and after passing the opposite
covered branch upward through the strands, the braiding is still further continued
down the main body of the conductor, until the junction c2 of wires a and b is.
reached, and the wire a is then continuously covered after passing the previously
covered end 6¹ upward through the strands as before. It will be seen that with
this method of applying the jacket, there are continuous strands and a continuous
enclosing fabric from one end of one of the branches, to the extreme end of one
of the branches at the opposite end of the complex conductor. With a little
practice, an ordinary operative can skillfully and rapidly apply these jackets in the
manner described, and secure desirable finish at the several junctions. It will be
seen that the conductor d with its strong insulating covering operates as a strength-
ening medium at the junction c, and that in like manner strengthening cords
applied to the several branches and junctions will prevent their rupture by strains
longitudinal therewith, but at right angles to the line of the main cord, or one of
its branches, as the case may be.
The advantages of this method of finishing the junction of the branches are of
course the same in conductors which have no cross cut conductor, and are provided
with but two wires with a junction as at c³ near both ends of the cord. The cross
cut conductor and its insulating jacket extending down one branch and up another,
serves as a-strengthening medium to prevent rupture at the junction c, and a strong
twine applied in like manner to the extreme ends, will strengthen the junction c¹
and c², so that no ruptures will be liable from strains on the branched ends applied
at right angles to the line of the cord beyond the junctions. Although only one
conductor of a complex character is shewn, it is to be understood that the tips
hereafter described are for general service on flexible electric cords, whether they
contain one or more conducting wires or sets of wires.
You will observe by the Drawings that several forms of tip wires are shown;
instead of being round wires as heretofore, they are either preferably square or
triangular in section. The round wires are capable of maintaining but two points
of electric contact, one of which is with the post, and the other diametrically
opposite with the screw. It will be seen that the triangular tip wire will afford one
point of contact with the screw on one edge, and two points with the post, and the
same is true of the square tip wire. Moreover the improved form of tip wire is
held much more firmly in the post than is possible with the round wire; round
tapered tip wires have heretofore been used, but these work loose, and become easily
detached.
In the last four Figs. the shell is shewn in section to expose the tip wire and
conductor. Similar letters indicate like parts in the several Figs. :-
B is a brass or other suitable sheet metal shell made in any desirable manner
and having its open end slightly flared to prevent abrasion of the braided covering
of the cord; the practically closed or forward end of the shell has a central hole or
perforation adapted to permit the passage of the tip wire C which is formed as
shown, with an eye e through which the core wire is threaded, and enlarged around
the eye, as seen at f, so that the said portion will just fit snugly the inside of the
shell B; behind the eye e is a short tail g, h is the metal conductor of the cord as
before described, and i is the braided covering.
Figs. 4 and 5 illustrate the manner of attaching the tip wire, which constitutes in
first cutting away the binder and braided covering of the cord, exposing the wire h,
which is then passed or threaded into the eye e or hook end of the tip wire, and
bent back upon the tail g or upon itself, according to the character of the tip wire
employed; the forward end or point of the tip wire is then forced through the hole
in the front end of the shell, the tip wire being sufficiently longer than the shell;
the produding end or point of the tip wire is then grasped and drawn forward,
until the swell around the eye, reaches the front end of the shell, as shown in dotted
lines at Fig. 4, and solid lines at Fig. 5. The relative diameters of the tip wire and

page_text: the hole in the forward end of the shell, and the swell at the eye, and the inside
diameter of the shell being such that when drawn to the position shown in Fig. 5,
they will bind snugly. When the tip wire is in the position just described, it will
have drawn the braided portion of the cord within the shell, and the latter is then,
by means of a suitable press, crimped just behind the eye of the needle, as shown
at k, whereby the conducting wire is pinched between the walls of the shell and
the tip wire, to produce perfect contact between the three, and the tip wire is also
firmly held in place against vibration; and in order that the braided covering may
be insured against slipping back upon the conducting wire, and also to form a
secondary grasp upon the cord as a whole; the shell is also crimped at l. The
result of the two crimpings accomplishes the objects sought, and makes a strong
stiff joint and perfect contact of metals. The projecting end or point of the
needle, if too long, may be clipped off at any suitable or desirable distance from the
shell:-
At Figs. 7, 8, and 9, the tip wire is shown with different formations of the eye or
hook; and these are only designed to show a few of many different ways in which I
have applied the principle of my Invention, preferring in practice to use the form
shown in Figs. 4, 5, and 6.
The point of the needle may be bent, as shown in dotted lines at Fig. 8, to adapt
it to some kinds of posts, many other changes will suggest themselves which may
be made without departing from the spirit of my Invention, and I do not therefore
wish to be understood as at all limiting myself in this direction, nor in the exact point
within the shell, where the eye of the needle is secured, as it may be immediately
adjacent to the forward end, or at any point between the front and back ends, and
the shell crimped behind the eye or behind and in front of, the same, as clearly
shown at Fig. 10, in which case the shell would have a practical swell between the
grooves or crimps. I do not wish to be understood as confining myself to a
seamless shell, for although I prefer such a shell, they may be made with a longitu-
dinal seam.
It will be seen that if two tip wires at the opposite ends of a cord be grasped, and
tensile, strain applied to the cord, that their firm connection with their shells and
the strong insulating jacket will cause the latter to bear the strain to the relief of
the conducting wires, and therefore these can seldom, if ever, be injured by such
strains. It is not to be understood that a round tip wire cannot be used with the
tip shell constructed and applied as shewn, but that the square or triangular form
is of greater value. The tip wires and their shells are so readily applied to cords
that they can be profitably manufactured and sold as articles of trade. The use of
solder as heretofore for uniting the conducting wires and tip wires is objectionable
in many respects, and it will be seen that by these improvements it is wholly
obviated, and a perfect metallic contact attained. It will also be seen that ends of
the braided or woven jackets are fully protected, and a fine neat finish afforded.
Having now described the nature of the said Invention, and in what manner the
same is to be performed, what I claim as the Invention is,-
1st. A branched telephone conductor provided with an exterior braided or woven
jacket which is a continuous fabric at the junction of the branches, and extends
continuously from or to the end of one of said branches, substantially as described,
whereby a strong, neat, and desirable exterior finish is attained at said junctions,
as set forth.
2nd. An electric telephonic conductor or switch cord containing two or more
insulated electric conductors, which are branched from the main body of the cord,
and have an exterior braided or woven jacket which is exposed of strands con-
necting continuously from the end of one branch throughout the length of the
cord, and terminating at the end of another branch, substantially as described.
3rd. A branched telephone conductor or switch cord provided with a strengthening
cord which extends down one branch to the junction of the branches, and thence
upward on another branch, substantially as described.
"

page_text: 4th. A telephonic conductor containing two main electric conductors insulated
and united in one jacket, branched midway, and containing in each branch one of
the main conductors, and a cross cut conductor which extends from the end of one
branch to its junction with the main cord, and thence to the end of the other
branch, substantially as described, whereby the cord may be used with a pair of
telephones, and the several conductors be united and convenient for use, as set
forth.
5th. The combination in a flexible jacketed electric conductor, of one or more
conducting wires, a tip wire, and an enclosing shell which firmly unites the jacket
and tip wire, substantially as described.
6th. As a new article of manufacture, a tip for flexible electric conductors con-
sisting of a metallic shell and a metallic tip wire, the latter adapted to carry the
core of the cord within the shell, and to be secured in place, substantially as
herein-before described.
7th. The method herein described of securing metal tips to switch cords, and
producing conductivity by compressing the outer shell, and confining the core
between the said shell and an interior spear or needle.
8th. In combination with a flexible electric conductor, a tip wire of rectangular
or triangular form in cross section, substantially as and for the purposes set forth.
In witness whereof, I, the said George John Stanford, have hereunto set my
hand and seal, this Eleventh day of September, in the year of our Lord
1878.
GEORGE JOHN STANFORD. (L.S.)