IMPROVEMENTS IN AND CONNECTED WITH FUSES FOR BLASTING PURPOSES
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by Adam Hunter and John Hunter at
the Office of the Commissioners of Patents on the 23rd August 1881.
ADAM HUNTER and JOHN HUNTER, both of Glasgow, in the County of Lanark,
North Britain. "IMPROVEMENTS IN AND CONNECTED WITH FUSES FOR BLASTING
PURPOSES."
This Invention relates to improvements in and connected with fuses for blasting
purposes, designed to enable mining, quarrying, and similar operations to be carried
on with greater safety or security to life when gun-powder, gun-cotton, or similar
explosive agents are used.
The Invention comprises a new or improved construction of fuse combined with
a slow burning match specially prepared to ensure firing of the fuse, while the fuse
is also fitted and applied in the bore or drift in such a manner that the blasting
cartridge will be exploded within a fixed interval after lighting the match,
and if the fuse has not acted there shall be no danger attending the fitting of a
new one.
In blasting rock in quarrying, or coal or other mineral in mining, as usually
practised the cartridge is placed at the bottom or inner end of the blast, drift, or
hole, and a needle or wire inserted into the cartridge and extending outside of the
drift is left in that position until the hole has been tamped or plugged with clay or
other material. This needle or wire is then withdrawn, and a straw filled with
gun-powder is inserted into the opening left, and is pressed in till it reaches the
cardridge.
This straw tube fuse is then fired by a slow match; and if moisture or any
obstruction cutting the straw prevents the whole length of the fuse firing at
once, but allows of slow combustion of the moistened powder or of the broken
straw, the lives of the workmen may be endangered by the returning to examine
the tamped blast hole.
By the present improvements such a risk is obviated by the use of a fuse
consisting of a short tube of waterproof paper, which is filled with fine powder or
similar explosive, and is inserted only a few inches within the small hole left by
the needle or wire. This fuse is made with a close end or bottom for convenience
of carriage or transport, but when inserted the end is broken off so that there may

page_text: be a free passage from the gun-powder in the fuse tube, and through the
entire length of the wire hole to the pricked cartridge. The fuse when fired must
in this way act at once on the cartridge. by communication through the wire hole,
or if there is any interruption the fuse is certain to be fired and become extinct
without acting on the cartridge. The wire can be reinserted and a new fuse then
applied without danger. The outer end of the fuse is twisted to retain the powder
within the tubular part, and this twisted paper is left of sufficient length and
saturated with a solution or composition to form the firing match or slow burning
part of the fuse.
The solution which we employ for this purpose is varied according to the
circumstances in which the fuses are to be used. When the match is to be a slow
one we use nitrate of potash or soda, chlorate of potash, or other similar salt, or an
admixture of such salts dissolved in water and saturate the match or twisted end
of the fuse therewith, a short length of the fuse tube being by preference also
dipped. When the fuse is to be used in mines where explosive gas may be
escaping from the mineral, the match formed by dipping in solution of nitre is
particularly applicable as it may be fired without a flame by applying burning
match paper or a portion of the match torn off, and to which the light has been
applied at some distance from the scene of operations. When the match is not
intended to be slow in action we prefer to use melted sulphur, spirits, paraffin, or
other inflamable substance, into which we dip the match and end of the fuse and
allow it to dry. The tube of the fuse is made by rolling bands of paper spirally or
longitudinally on wires or mandrels into cylinders of about one tenth of an inch
or thereby in diameter, the last part of the roll being gummed or pasted, and the
tube afterwards varnished or coated with a water proof solution.
When working in wet or moist ground, and there would be a liability of the
hole made by the needle or wire filling with water or becoming choked, a metal
tube is tamped in the drift or blast hole reaching down to the cartridge, and the
fuse is inserted within this metal tube or barrel.