Improvements in Electric Fuses.
Year: 1885

page_text: .
Improvements in Electric Fuses.
We, JAMES MACNAB of 39 Mortimer Street, Cavendish Square, in the County of
Middlesex, Engineer, and DANIEL HICKIE of 23 Queen Anne's Gate, Westminster
in the County of Middlesex, Mining Engineer, do hereby declare the nature of
our Invention for IMPROVEMENTS IN ELECTRIC FUSES to be as follows:-
Our invention relates to improvements on the present methods of constructing
low and high tension electric fuses for the purpose of insuring greater reliability of
action and more efficiency in manufacture, also for securing more freedom from
damage and better contact between the poles of the same than has hitherto been
obtained, besides neutralizing any chemical action or decomposition that might
take place between the guncotton or priming, composition employed and the sub-
stances of which the plug or wire-holder case is composed, and on the end of which
is fixed the copper shell case of the detonator cap, or when simple ignition only is
desired, by preventing metallic or other contact and absolutely keeping the same
apart, in low tension or platinum bridge system, with a non conducting material of
a permanent character which resists climatic influences or chemical action and
completely insulates the same without risk of destroying the efficiency or igniting
qualities of the fuse, and also firmly protects the platinum wire-bridge from being
broken or damaged either in handling in practice, in transit, or in storage, and for,
the better prevention of displacement of the fuse wires; parts of which are also
applicable in constructing high tension electric fuses, including an improved method
of attaching the short fuse wires to the connecting wires. For this purpose we
construct the low tension fuse plug or wire-holder case of glass, by preference, or
other suitable material, and in a hollow tubular form, with each end open and of a
suitable diameter and length to fit the interior bore of the copper shell case of the
detonator cap which is pressed into position on one end of the hollow glass tube
case, and on the other end we form a projecting circular rim or lip, made slightly
larger than the interior diameter of the copper shell case, to prevent the fuse plug
case from being forced too far down on the top of the fulminate of mercury charge
which it contains, or otherwise modified and arranged for this special purpose.
The two connecting wires are cut to the required length and placed the usual
distance apart from each other in the interior bore of the plug or glass tube case,
and firmly held in position there with the terminals projecting beyond the end of
the glass tube case, and is then charged with a suitable non-conducting substance

page_text: such as a mixture of resin and glue "Spences metal," glue whiting and alum, shellac
and whiting, or other suitable material, reduced to a liquid state by heat, or other-
wise prepared in a plastic or other form, and capable of being quickly solidified,
when it is run in or pressed into the glass tube case to surround the two wires in
its interior, and rigidly secure and insulate them in the tube case in a solid manner.
After the composition or insulating material bas set hard the terminals are cut to
the required lengths and prepared for being bridged with fine platinum wire. For
this purpose we split or perforate a hole in each terminal at the extreme point, and
in these splits we place the platinum wire, or it may be threaded through the holes
instead when such are used; after this operation each terminal split is pressed
tightly together till the platinum wire ends are firmly caught or jammed in the
terminal wires or rigidly fixed in the perforated holes, as the case may be, or the
terminals may be bent over instead at each end and the platinum wire jammed or
caught in the manner above described, and may be soldered as well or cemented
with shellac varnish, if desired, to insure more perfect contact.
When the terminal end of the plug-case containing the platinum wire-bridge is
firmly secured it is dipped into a bath of a suitable thickness of shellac varnish or
other similar-acting non-conducting inflammable liquid material, or the plug-case
may be entirely immersed in the bath up to the connecting wires which pass
through the head or rim end of the plug-case, and afterwards hung up to evaporate
the alcohol or solvent, when it will thus be double insulated, and the core or column
of non-conducting material in its interior cut off from climatic influences or contact
with the priming, including the wire ends and platinum bridge, which latter, when
the shellac varnish sets hard, will be rigidly kept in position and protected from
damage or breakage while being pressed into the shell case of the detonator cap, or
in rough handling, or in transit.
For securing extra sensitiveness especially when several fuses are simultaneously
fired, we also mix the shellac varnish with fine powdered tonite or guncotton, or
other suitable priming which can be easily ignited at a low temperature. All wires
being thus insulated there is no liability whatever of a short circuit being formed
should the terminals accidently be in contact with the walls of the copper cap
case.
In the special case of gutta percha or india rubber covered wire and in lieu of
above described method we insert or jam the insulated wire ends into the glass
tube case, side by side, and secure them in position with a cement of gutta percha
or glue, whiting and alum in a plastic state or other suitable cement, when the
gutta percha covering of each wire will insulate and keep them the proper distance
apart, the bared terminals are then bridged with platinum wire and dipped in
shellac varnish as previously described.
.
The platinum wire bridge, if desired, may be soldered down on the terminal ends
in the usual way, and then dipped or coated with shellac varnish in a similar manner
to that already described.
For simple ignition with low tension fuse, as described, we use an outer case of
glass, instead of the above detonator cap, of a similar diameter and length to the
copper shell case, and charged with dry fine-grained gunpowder or in a liquid form
and dried in its interior, or a shell case of copper or other suitable material may
be substituted for the glass shell case.
In constructing high tension fuse the same principles and general method of
making the low tension fuse cases are employed, but instead of the platinum wire
bridge the usual explosive priming composition is employed in the interior of the
glass plug case, which is arranged to contain the core or column with the two fine
wire terminals moulded or cemented in, as already described, and placed in its
interior, or the usual gutta percha column may be used instead, and is cemented or
moulded in the head or rim end of the glass tube case with the terminals embedded
in the priming composition, which is closed in with a plug or disc of cardboard
tipped or dipped in safety match composition or other inflammable composition,
and the entire fuse case then dipped or immersed in a bath of shellac or sealing-wax

page_text: varnish, or in gutta percha cement, to protect the interior priming from water or
climatic influences.
The ordinary high-tension primers, if desired, may be used instead and jammed
in the glass case, and the head fixed in with a plug of gutta percha or other suitable
material.
When the connecting wires are attached and the plug case furnished with a
detonator cap complete, the entire fuse case and cap are coated or dipped in gutta
percha cement or other suitable waterproof varnish.
For greater ease and simplicity in manufacturing or attaching the two connecting
ends of the fine terminal wires of the primer to the ends of the connecting wires
which are annealed and then hammered out or rolled flat to admit of the two fuse
ends being spliced to them, when two holes are perforated in each end for threading
the fine copper wires in and out to thus firmly hold them in position and contact,
they are then compressed or folded down flat and the ends twisted round the
connecting wires or otherwise.
This is also attainable by short pieces of flattened wire or "splicers," and perforated
or punched in either end to take the fuse wires and connecting wires in the same
manner, and are then covered or embedded in gutta percha tissue and cemented
down.
The above glass tube case may be lengthened or drawn out to contain a charge
of fine-grained gunpowder, in addition to the priming, for firing guns, or the usual
quill or copper tube of gunpowder composition may be substituted, and cemented
on or otherwise fixed on the fuse case end.
Besides the advantages of extra strength and permanency in the glass plug case
and materials employed, these improvements secures perfect insulation and a greater
ease in manipulation and rapidity in the manufacture, being also waterproof all
climatic action is neutralized and cut off from the interior substances of which
these and the ordinary made electric fuses are composed and deterioration of same
thus prevented in storage or in transit. More reliable ignition is also obtained and
consequently less miss-fires in practice, as compared with the present methods of
making electric fuses.
Dated this bee fauentl

page_text: JAMES MACNAB of 39 Mortimer Street, Cavendish Square, in the County of
Middlesex, Engineer and DANIEL HICKIE of 23 Queen Annes Gate, Westminster,
in the County of Middlesex, Mining Engineer, do hereby declare the nature of our
said invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:-
Our Invention relates to improvements in the present methods of constructing
low and high tension electric fuses for the purpose of insuring greater reliability
of action and more efficiency in manufacture, also for securing more freedom from
damage and better contact between the poles of the same than has hitherto been
obtained, besides neutralizing any chemical action or decomposition that might
take place between the guncotton or priming composition employed and the
substances of which the plug or wire-holder case is composed, and on the end of
which is fixed the copper shell case of the detonator cap, or when simple ignition
only is desired, by preventing metallic or other contact and absolutely keeping the
same apart, in low tension or platinum bridge system, with a nonconducting
material of a permanent character which resists climatic influences or chemical
action and completely insulates the same without risk of destroying the efficiency
or igniting qualities of the fuse, and also firmly protects the platinum wire bridge
from being broken or damaged either in handling in practise, in transit, or in
storage, and for the better prevention of displacement of the fuse wires; parts of
which are also applicable in constructing high tension electric fuse, including an
improved method of attaching the short fuse wires to the connecting wires.
For this purpose we construct the low tension. fuse plug or wire-holder case of
glass, or other suitable material, and in a hollow tubular form, with each end open
and of a suitable diameter and length to fit the interior bore of the copper shell
case of the detonator cap which is pressed into position in one end of the hollow
glass tube case, and on the other end we form a projecting circular rim or lip, made
slightly larger than the interior diameter of the copper shell case, to prevent the
fuse plug case from being forced too far down on the top of the fulminate of
mercury charge which it contains, or otherwise modified and arranged for this
special purpose.
The two connecting wires are cut to the required lengths and placed the usual
distance apart from each other in the interior bore of the plug or glass tube case,
and firmly held in position there with the terminals projecting beyond the end of
the glass plug case, and is then charged with a suitable nonconducting substance
such as a mixture of resin and glue, Spences metal, glue whiting and alum, shellac
and whiting, or other suitable material reduced to a liquid state by heat or
otherwise prepared in a plastic or other form, and capable of being quickly
solidified, when it is run in or pressed into the glass tube case to surround the two
wires in its interior, and rigidly secure and insulate them in the tube case in a
Bolid manner. After the composition or insulating material has set hard the
terminals are cut to the required lengths and prepared for being bridged with fine
platinum wire.

page_text: For this purpose we split or perforate a hole in each terminal at the extreme
point, and in these splits we place the platinum wire, or it is threaded through the
holes instead when such are used; after this operation each terminal split is pressed
tightly together till the platinum wire ends are firmly caught or jammed in the
terminal wires or rigidly fixed in the perforated holes, as the case may be, or the
terminals may be bent over instead, at each end and the platinum wire jammed or.
caught in the manner above described, and may be soldered as well or cemented
with shellac varnish or other suitable substance, if desired, to insure more perfect
contact. When the terminal end of the plug case containing the platinum wire
bridge is firmly secured it is dipped into a bath of a suitable thickness of shellac
varnish or other similar-acting nonconducting inflammable liquid material, or the
plug case may be entirely immersed in the bath up to the connecting wires which
pass through the head or rim end of the plug case, and afterwards hung up to
evaporate the alcohol or solvent, when it will thus be doubly insulated, and the
core or column of non-conducting material in its interior cut off from climatic
influences or contact with the priming, including the wire ends and platinum
bridge, which latter, when the shellac varnish sets hard, will be rigidly kept in
position and protected from damage or breakage while being pressed into the shell
case of the detonator cap, or in rough handling or in transit. For securing extra
sensitiveness especially when several fuses are simultaneously fired we also mix the
shellac varnish with finely powdered tonite, guncotton, or other suitable priming
which can be easily ignited at a low temperature-All wires being thus insulated
there is no liability whatever of a short circuit being formed should the terminals
accidentaly be in contact with the walls of of the copper cap case,
In the special case of gutta percha or india rubber covered wires, and in lieu of
above described method, we insert or jam the insulated wire ends into the glass
tube case side by side and secure them in position with a cement of gutta percha
or glue, whiting, and alum, in plastic state or other suitable cement, when the
gutta percha covering of each wire will insulate and keep them the proper distance
apart; the bared terminals are then bridged with platinum wire and dipped in
shellac varnish as previously described.
The platinum bridge, if desired, may be soldered down on the terminal ends in
the usual way, and then dipped or coated with shellac varnish in a similar manner
to that already described.
For simple ignition with low tension fuse, as described, we use an outer case of
glass, instead of the above detonator cap, of a similar diameter and length to the
copper shell case, and charged with dry fine-grained gunpowder or in a liquid form
and dried in its interior, or a shell case of copper or other suitable material may be
substituted for the glass shell case.
In constructing high tension fuse the same principles and general method of
making the low tension fuse cases are employed, but instead of the platinum wire
bridge the usual explosive priming composition is employed in the interior of the glass
plug case, which is arranged to contain the core or column with the two fine wire
terminals moulded or cemented in, as already described, and placed in its interior,
or the usual gutta percha column may be used instead, and is cemented or moulded
in the head or rim end of the glass tube case with the terminals embedded in the
priming composition, which is closed in with a plug or disc of cardboard tipped or
dipped in safety match composition or other inflammable composition and the entire
fuse case then dipped or immersed in a bath of shellac or sealing-wax varnish, or
in gutta percha cement, to protect the interior priming from water or climatic
influences. The ordinary high tension primer, if desired, may be used instead and
jammed in the glass case, and the head fixed in with a plug of gutta percha or other
suitable material.
When the connecting wires are attached and the plug case furnished with a
detonator cap complete, the entire fuse case and cap are coated or dipped in gutta
percha cement or other suitable water-proof varnish,

page_text: For greater ease and simplicity in manufacturing or attaching the two connecting
ends of the fine terminal wires of the primer to the ends of the connecting wires,
which are annealed and then rolled or hammered flat when two holes are perforated
in each end to admit of the two fuse wire ends being spliced to them and for
threading the fine copper wires in and out to thus firmly hold them in position
and contact; they are then compressed or folded down flat and the ends twisted
round the connecting wires or otherwise-This is also attainable by short pieces of
flattened wire or "splicers," and perforated or punched in either end to take the
fuse wires and connecting wires in the same manner; and are then covered or
embedded in gutta percha tissue and cemented down-The above glass tube case
may be lengthened or drawn out to contain a charge of fine-grained gunpowder in
addition to the priming, for firing guns, or the usual quill or copper tube of gun-
powder or composition may be substituted, and cemented on or otherwise fixed on
the fuse case end.
Besides the advantages of extra strength and permanency in the glass plug case
and materials employed, these improvements secure perfect insulation and a greater
case in manipulation and rapidity in the manufacture, being also waterproof all
climatic action is neutralized and cut off from the interior substances of which these
and the ordinary made electric fuses are composed and deterioration of same thus
prevented in storage or in transit.
More reliable ignition is also obtained and consequently less miss-fires in practice
as compared with the present methods of making electric fuses.
In order that our said Invention may be clearly understood and readily carried
into effect we will proceed to more fully describe the same and also the sheet of
drawings hereunto annexed :-
In constructing these improved electric fuses we employ a hollow case or holder
of a nonconducting substance for containing the two terminal wires and in which
they are firmly encased with a nonconducting cement to hold them firmly in position
side by side, the two insulated wires with their terminals bared may be either
twisted together and jammed in or they may be fixed parallel and separately in
the said hollow case-holder and the nonconducting cement or material run in if
used in a liquid form or cemented in if in a plastic state. The cement or composi-
tion may be composed of resin and thin glue, Spences metal (Portland cement and
sulphur), glue whiting and a little alum, shellac and whiting, sulphur and resin, or
other suitable composition reduced to a liquid or plastic state, adopting whichever
method may be found most desirable to secure the success of the operation. The
hollow case or holder referred to for securing the wires may be made of glass, while
in the form of a hollow cane or tube, well-sized or cemented paper and wood pulp,
hornglass, vulcanite, in a plastic state, and moulded or compressed to secure the
correct diameter, shape, and necessary conditions to hold the wires, or well-seasoned
ebony, teak, or other wood; also rods of vulcanite or hornglass in a hardened
condition, or solid papier maché may be substituted and turned down in a lathe
to the necessary diameter and requirements and containing a hole drilled from end
to end of the case, or other suitable nonconducting material may be treated in a
similar manner. When paper is employed in a pasted or cemented state and rolled
on a fine central core or cylinder it is first cut into suitable lengths and while in a
semi-damp condition it is compressed in a mould to the desired diameter and form,
then allowed to slowly dry hard.
When the case or holder A Fig. 1, is ready for placing the wire in its interior
the wires C¹ are twisted near the bared terminals C and jammed or fixed in
position in the case A and cemented in with shellac varnish or other similar cement
and the unfilled space in the terminal point D of the case is closed up with a plastic
binding cement composed of gluc, chalk, and alun, or other suitable composition,
and allowed to solidify, after which the terminals C are bridged with fine platinum
wire, and soldered down in the usual manner, or the terminal ends may be flattened
and perforated or split, after which, the platinum wire bridge is fixed or plaited in

page_text: the perforations E or splits, as the case may be, to ensure contact and the terminals
compressed to hold the platinum wire ends firmly in their place, and may be further
secured with a touch of shellac varnish or soldered down. After this operation
the delicate platinum wire may be further secured and protected from being
broken or damaged and also insulated by dipping it in a thin solution of shellac
varnish incorporated with finely pulverized or powdered cotton powder, guncotton,
in liquid resin, liquid sulphur, or in a. solution of thin shellac varnish and ful-
minate of mercury, or to secure greater rigidity of the platinum bridge and more
perfect contact with the fulminate the same may be poured or placed round the
platinum bridge by employing an open ended detonator cap case after the electric
fuse has been first cemented into the other open end the fulminate is then fixed or
placed in position in the usual way, and closed in with a short copper cap, plug, or
cover, sealed in with shellac or other varnish. To further protect the platinum
bridge A Fig. 4 in charging with priming B and make the transport and use of
such fuse more secure, we place the two bared terminals C in a disc or plug D of
papier maché or wood containing two holes E suitably guaged in which the bared
wire points C are fixed, and the insulated part of the wires F in the case-holder G
are twisted, to firmly keep them in position, and are cemented in as already
described, but in this special modification the case-holder G is made longer to admit
of a recess or socket holder H being left at the point of the case-holder G to
encircle and securely protect the platinum bridge A and also for holding and
regulating the quantity of priming B which is adjusted in the case G and suitably
sealed in.
In this example the fuse case-holder G point is placed down in the fulminate
cap or detonator case II and when thus arranged perfect contact and protection
of the delicate bridge A is secured, and risk of touching the fulminate J with the
wires or terminals avoided and regularity of the priming charge ensured. It can
also be made to form the detonator in itself by priming it with detonator com-
position or it can be filled with ordinary priming for general use.
The outer case,
fixed as described, would be a guide for the priming charge and a safe-guard
against accident.
For filling the cases with the fulminate in the latter modification the moulding
frame (Fig. 3) may be used to hold them securely in position for charging, when
the fuse heads are inverted in the frame and their cases placed in the wire holder
holes at the top and the fuse wires allowed to hang downwards, or other suitable
method may be employed.
Any other suitable protecting inflammable substance may be used instead, the
platinum bridge may, if desired, be dipped in shellac varnish alone and employed
only where one or two simultaneous shots are fired, but when dipped in liquid
sulphur or fulminate preparation a greater number may be fired in circuit..
Where a gutta percha or other heavily covered wire is used it is slightly
softened by heat in a flame and jammed into the case-holder, and when it has
cooled will cement or hold itself in the interior of the case and may be touched at
the head with shellac varnish and cemented at the point and treated as already
described. In making high tension fuse Fig. 2, the usual column of gutta percha C
in which the terminal wires A are embedded is cemented in the case-holder B with
the ordinary priming or firing composition D and the case end closed with a plug
of liquid gunpowder E, liquid sulphur, or other inflammable composition in a
plastic state, and when thoroughly dry the end F or point is afterwards. dipped
in thin shellac or other varnish, to protect the action and keep the same damp-
proof. The advantages of the socket holder or protecting case, as already described,
apply with equal efficiency as with low tension fuse. For greater convenience and
simplicity in attaching the two fine copper wires A of the primer to the ends of
the main connecting wires G the bared ends of the latter are annealed and rolled
or hammered flat to enable them to be perforated with two holes H in each
end to admit of the two fuse wire ends A being spliced to them and which
are threaded in and out. in. the two holes Hof each main connecting wire end-G

page_text: and then pressed close on the flat ends to thus firmly hold them in position and
in contact, the projecting fine wire end is twisted round the main connecting wire G
if necessary, they are then covered separately with gutta percha tissue I and
afterwards embedded or cemented together to cover the joint J and the two main
connecting wires G twisted together for about two inches or more above the joint J
to strengthen and keep it from being accidentaly torn apart.
Figure 3, represents part of a longitudinal elevation in section of the moulding
frame for holding the fuse case-holder A and wires B firmly in position; in this
process the terminal wires C are placed side by side and parallel to each other in
the interior of the case-holder A for the purpose of running in the cement compo-
sition D for surrounding or embedding them firmly. The wire points C are first
inserted into the two holes F or series of two holes F1, F2, placed apart to cor-
respond with the required distance they are to be kept separate and are perforated
to the diameter of the wires B in a flat plate G of tinned iron or other metal and
the plate screwed down on a board H or bed of wood. This frame may have two
parallel sets of holes or as many as may be conveniently required to mould or run
in the composition at one operation and is fitted with a top frame or holder I with
holes J in which the two connecting ends of the wires B are placed to keep them
upright and in position while the liquid composition is being poured in; flat
stays of wood K should be placed between each two wires B to keep them apart
and to admit of the operation of running in the composition being easily carried
out, this is best attained when two series of rows are employed as the flat wood
stays J are kept rigid by the opposite or parallel row of wires and which are placed
in position after the case-holders are fixed ready for moulding in the wires. After
the composition has become hard the moulded fuse are then taken out of the frame
and the same operation repeated until the required number are made. We bare
the insulated wire terminals more rapidly and efficiently than by the usual
method by holding the wire point in a gas or wick flame for a moment to burn
or soften the insulation or covering and then instantly and at one operation scrape
or force off with a knife the thread, gutta percha, or other covering.
For ensuring accuracy in and facilitating the cutting of the fuse wires we
employ a cutting frame (Fig. 5.) in which are combined a reel A for holding and
unfolding one or more fuse wire coils B, two spindles C working in an upright
bearing D the top one slightly weighted to keep the wire E taut and in position to
admit of their being pulled out to the required lengths, a special cutting knife F
working on a pivot G and actuated by a spring which holds it upright, a fixed
horizontal cutting blade II on which the wires E rest, and a movable gauge J
which is set to the required length from the cutting point K. The above
described cutting apparatus may be placed on a suitable bench L to hold it in
position.
The wires held in position as above are pulled out to the gauge each time when
the operation of cutting is then accomplished by pulling down the knife by the
hand, or otherwise, on the wires resting and held on the horizontal blade, which
then severs them in an efficient manner.
Having now particularly described and ascertained the nature of our said
Invention and in what manner the same is to be performed we declare that
what we claim is
First. The combination with low and high tension fuses of a hollow case-holder
with a projecting rim or lip and made of glass, wood, or other nonconducting
material, for encasing and holding the electric fuse wires as arranged for the purpose
enumerated, substantially as herein described.
Secondly. The method of fixing the platinum bridge in terminals perforated
with holes, and also protection of the "bridge" by dipping in an inflammable
composition for the purpose stated, substantially as herein described.
Thirdly. The combination and employment with low tension fuse of a case-
holder with a rim or lip, and having a recess or socket-holder in its point, for

page_text: containing and regulating the priming charge and for protecting the "bridge
from damage, substantially as herein described.
"
Fourthly. The use and combination of a case-holder with a detonator cap shell
case open at both ends, for efficiently protecting and embedding the "bridge" in
fulminate composition for the purpose stated, substantially as herein described.
Fifthly. The system of splicing the fine connecting terminal wires of high
tension or other fuse to the main connecting wires, and also the method of
instantly stripping the insulation from the wire points, substantially as herein
described.