IMPROVEMENTS IN TORPEDOES OR SUBMARINE MINES
Year: 1883

page_text: LETTERS PATENT to James Mathieson Electrical Engineer of 74 Romford
Road Stratford in the County of Essex for an Invention of "IMPROVEMENTS
IN TORPEDOES OR SUBMARINE MINES
"
PROVISIONAL SPECIFICATION left by the said James Mathieson at the
Office of the Commissioners of Patents on the 15th October 1883.
JAMES MATHIESON Electrical Engineer of 74 Romford Road Stratford in the
County of Essex. "IMPROVEMENTS IN TORPEDOES OR SUBMARINE MINES
"
This Invention has for its object improvements in torpedoes or submarine
mines.
The invention applies to what are known as mechanical mines or mines to be
fired by contact with a passing vessel.
It is required for safety that such mines at the time of laying should be in an
inert condition and should remain so for some hours but become afterwards active.
I attain this end with certainty both as to maintenance of the inert state for a
sufficient time and the subsequent transition to the active condition. This I do
by the use of the metal mercury which I apply so that it may gradually dissolve
a stop or partition or restraining instrument made of zinc or other metal which is
soluble in mercury.
In one arrangement which I use I screw into the top of the torpedo a tube or
case projecting inwards and at the lower end of this case I provide a nipple armed
with a percussion cap, the parts being so arranged that the explosion of the cap
will fire the charge.
The tube or case is provided with a cover which screws in watertight.
Near the top of the case a hammer is provided it is suspended from the cover
by a stem or neck of vulcanite. This stem or neck is sufficiently strong to
maintain the hammer so long as it is not exposed to violence but if, whilst the
torpedo is in the active state, a vessel collides with it the stem or neck of vulcanite
which weakened by nicking snaps and the hammer falls.
My arrangements to maintain the torpedo for a sufficient time in an inert
condition and afterwards to render it active are as follows:-The hammer which I

page_text: employ is hollow and when the torpedo is laid it is empty. In this state, it is so
light that its inertia is insufficient in any case to break the neck by which it is
suspended.
On the top of the cover I provide a metal bottle or receptacle for mercury, it is
closed at the bottom and separated from the cavity of the hammer by a disc of
zinc. As soon as the mercury is placed in contact with the zinc it commences to
dissolve it and in the course of a few hours-more or less according to the thickness
of the zinc employed it eats a hole in the zinc and runs through into the cavity
in the hammer. When the hammer is thus filled its weight and its inertia become
sufficient.
For further security I insert within the hollow hammer a toggle usually made
of copper wire, it is securely fixed at its upper end and at its lower end within the
hollow hammer it is provided with a button of solder which is larger than the
passage in the vulcanite neck by which the hammer is suspended. Hence the
hollow hammer cannot fall far so long as the button is intact.
When however the mercury has descended into the cavity in the hammer it
commences to dissolve the button and soon the hammer is only restrained by the
brittle neck by which it is suspended.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said James Mathieson in the Patent Office on the 15th April 1884.
JAMES MATHIESON Electrical Engineer of 74 Romford Road Stratford in the
County of Essex "IMPROVEMENTS IN TORPEDOES OR SUBMARINE MINES
"
This Invention has for its object improvements in torpedoes or .submarine
mines,
The Invention applies to what are known as mechanical mines or mines to be
fired by contact with a passing vessel. It is required for safety that such mines
at the time of laying should be in an inert condition and should remain so for
some hours but become afterwards active.
I attain this end with certainty both as to maintenance of the inert state for a
sufficient time and the subsequent transition to the active condition. This I do
by the use of the metal mercury which I apply so that it may gradually dissolve a
stop or partition or restraining instrument made of zinc or other metal which is
soluble in mercury.
In one arrangement which I use I screw into the top of the torpedo a tube or
case projecting inwards and at the lower end of this case I provide a nipple armed
with a percussion cap, the parts being so arranged that the explosion of the cap
will fire the charge.
The tube or case is provided with a cover which screws in watertight. Near
the top of the case a hammer is provided it is suspended from the cover by a stem
or neck of vulcanite. This stem or neck is sufficiently strong to maintain the
hammer so long as it is not exposed to violence but if, whilst the torpedo is in the
active state, a vessel collides with it the stem or neck of vulcanite, which is
weakened by nicking, snaps and the hammer falls
My arrangements to maintain the torpedo for a sufficient time in an inert
condition and afterwards to render it active are as follows:-The hammer which I
employ is hollow and when the torpedo is laid it is empty. In this state it is so
light that its inertia is insufficient in any case to break the neck by which it is
suspended.
On the top of the cover I provide a metal bottle or receptacle for mercury it is
closed at the bottom and separated from the cavity of the hammer by a disc of
zinc. As soon as the mercury is placed in contact with the zinc it commences to
dissolve it and in the course of a few hours more or less according to the thickness
of the zinc employed it eats a hole in the zinc and runs through into the cavity in
the hammer
When the hammer is thus filled its weight and its inertia become sufficient.
In order that my said Invention may be most fully understood and readily
carried into effect I will proceed to describe the drawing hereunto annexed.
DESCRIPTION OF THE DRAWING
The drawing shews a vertical section of the priming chambers and firing
apparatus of a mechanical torpedo or submarine mine.
A is the cover of the torpedo, which when fixed in its place closes it water tight;
the form of the torpedo and the arrangement of the main charge within being as
hereinbefore.
B is a tube screwed into the cover A; it is of such a length as to give a
sufficient fall to the hammer C to enable it to fire the percussion cap, placed upon
the nipple D at the lower end of the tube B. The cap when so exploded ignites

page_text: the fuses E, E, fires the priming charge in the chamber F and insures the detonation
of the main charge in the body of the torpedo.
G, is a cover screwed into the upper part of the tube B; upon this cover a
chamber H to receive mercury is formed.
The chamber H has an aperture in the bottom, which is closed by means of a
disc of zinc I, held up to the aperture by means of the screw nozzle K. The lower
end of this nozzle is adapted to receive the vulcanite stem L. This stem screws
into the nozzle at its lower end, and it also screws into an aperture provided for it
in the top hollow hammer C. A groove is turned around the stem L, at L', in
order that the stem may break at this point when a blow of sufficient force is
struck upon the torpedo after the hammer has been loaded by the descent of the
mercury into it from the mercury chamber H.
Immediately before the torpedo is laid, mercury is poured into the chamber H
to fill it, and the chamber is closed by inserting a screw plug. The mercury then
finds itself in contact with the zinc disc I, and this it commences slowly to dissolve,
but a considerable time (measured by hours) will elapse before there is any risk of
the disc being perforated by the mercury, and all the operations connected with
the laying of the torpedo may therefore be conducted with safety. But after this
interval, when the zinc disc has been eaten through, the mercury pours down from
the chamber H into the cavity of the hollow hammer C, and thereby the weight
of this hammer, which before was insignificant is so increased that upon any heavy
blow being struck upon the torpedo its inertia will cause the fracture of the
vulcanite stem at the part L' where it is grooved. The loaded hammer then falls
upon the percussion cap, and the explosion ensues.
Having thus described the nature of my said Invention and the manner of
performing the same, I would have it understood that I claim―
First, My improvements in torpedoes or submarine mines consisting in the use
of mercury and another metal soluble therein to effect the passage of the torpedo
from the passive to the active condition, the arrangement being such that so long
as the latter metal remains undissolved by the former the hammer, by which the
firing of the charge is effected is securely retained, and will not be set free by the
impact of a passing vessel upon the torpedo.
Second. My improvements in and relating to the firing apparatus of mechanical
torpedoes or submarine mines substantially as herein described and illustrated by
the annexed drawing.
In witness whereof I the said James Mathieson have hereunto set my hand and
Beal this 11th day of April in the year of our Lord One thousand eight hundred and
eighty four,