IMPROVEMENTS IN THE CONSTRUCTION OF CONCUSSION FUZES FOR THE EXPLOSION OF PROJECTILES
Year: 1867

page_text: LETTERS PATENT to Edward Augustus Dana, of Brookline, in the County
of Norfolk, and State of Massachusetts, in the United States of America,
for the Invention of: "IMPROVEMENTS IN THE CONSTRUCTION OF CONCUSSION
FUZES FOR THE EXPLOSION OF PROJECTILES."
COMPLETE SPECIFICATION filed by the said Edward Augustus Dana.
at the Office of the Commissioners of Patents, with his Petition and.
Declaration, on the 23rd August 1867, pursuant to the 9th Section of
the Patent Law Amendinent' Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, EDWARD
AUGUSTUS DANA, of Brookline, in the County of Norfolk, and State of
Massachusetts, in the United States of America, send greeting.
WHEREAS I am in possession of an Invention for "IMPROVEMENTS IN THE
CONSTRUCTION OF CONCUSSION FUZES FOR THE EXPLOSION OF PROJECTILES," and
have petitioned Her Majesty to grant unto me, my executors, administrators,
and assigns, Her Royal Letters Patent for the same, and have made solemn
declaration that I am the true and first Inventor thereof.
NOW KNOW YE, that I, the said Edward Augustus Dana, do hereby
declare that the following Complete Specification, under my hand and seal,
fully describes and ascertains the nature of the said Invention, and in what-

page_text: manner the same is to be performed, in and by the following statement,
reference being bad to the accompanying Drawings making a part of this
Specification:-
:-
The nature of my Invention consists, first, in suspending a striker or friction
match carrier (longitudinally) in the friction chamber of a fuze in such a
manner that if the shell in which the fuze is placed strikes head on,
obliquely, or even sideways, the said match carrier shall by its own momentum
free itself and ignite the composition, and thus explode the shell.
Second, in the general combination and arrangement of the friction match
carrier, the match chamber, and the friction match mixtures.
Third, in the peculiar means adopted to prevent the carrier from being
liberated by any other force than that of the concussion of the shell when it
strikes a solid object, and to insure its being liberated by that force, and so
explode the shell.
The construction and arrangement of parts and their functions may be
briefly set forth as follows-The fuze stock has within it a friction match
chamber, which is cylindrical in form, and occupies a longitudinal position.
Within this chamber is suspended the carrier or striker supported by its ends,
so that it cannot come in contact with the walls of the chamber. unless freed
by some considerable shock. The rear end of this carrier is made conical, so
as to fit into a conical countersink made in the rear screw plug of the stock,
which forms for this end a fixed support. The front end of the carrier is held
by a short pivot or spindle having a conical point fitting into a corresponding
countersink in the end of the carrier; this spindle passes through the head of
the chamber in such a manner that it would he free to be thrust forward by
the momentum of the carrier if not confined by a small pin which passes
laterally through it and the walls of the stock. As this pin is to be cut by
the momentum of the carrier when the shell strikes its object and not before,
it should be made as strong as is compatible with this purpose. In case the
shell in which my improved fuze is fixed strikes "head on," then the direction
of the carrier would be directly forward against the pivot with sufficient
momentum to cut the pin. If the projectile should strike otherwise than
head on," thus obliquely or sideways, then the motion of the carrier would
be oblique to the axis of the fuze, but as the pivot has a conical end fitting a
conical, recess in the end of the carrier a lateral notion of the carrier would
cause a longitudinal motion of, the pivot, thus cutting the pin and leaving the
carrier free to strike the walls of the fire chamber. The fact that the carrier
in my fuze is suspended, as will be more definitely set forth hereafter, touching
no, part of the walls of the match chamber, and that its supports are, so

page_text: arranged that any shock except a rearward' one in a line of its axis will free it
and cause explosion, gives to my Invention a peculiar and distinctive nature.
The friction match composition may be compounded in one mixture and
applied either to the striker or the walls of the match chamber, the opposite
surface being roughed to produce the necessary friction for' ignition. I prefer
however, to separate these ingredients, and to apply a part of them to the
striker and a part of them to the walls surrounding the striker, which in this
case consists of a cylinder of sand paper inserted in the chamber. In addition
to the pin spoken of above I further provide against the danger in certain
cases of the strikers being liberated before the shell has passed out of the gun
by a short block of compressed mealed powder being' placed upon the upper
or outer end of the pivot spindle, and firmly held there by the screw plug in
the head of the fuze stock, this screw plug being perforated and charged
with a priming of mealed powder. The powder block being lighted by the
flame of the discharge consumes rapidly, but not before the shell is out of the
gun, and being consumed ceases to be an obstruction in the way of the
forward movement of the spindle when the shell strikes. I further provide a
set screw to be used instead of the powder block in rifled cannon projectiles
which have little or no windage in passing out of the gun, the said set screw
passing through the screw plug and bearing against the pivot spindle to retain
the latter in position against the danger of handling and transportation, and
which is to be removed before firing.
The following is a description of that form of embodiment of this Invention
which is shown in the Drawing herewith accompanying and making a part of
this Specification, which is sufficiently clear and exact to enable others skilled

page_text: fastened into the shell, and having two recesses P, P, in its top to receive the
prongs of the screwdriver; B is the friction match carrier or striker centrally
held in the lower chamber L of the fuze stock, its rear end fitting into a
countersunk recess in the screw plug K, and its forward end receiving and
being held by the conical end of the pivot spindle C; K¹ is a screw plug
fitting into the rear end of the fuze stock, having perforation in its centre
and a countersunk recess in the centre of its interior face to receive the lower
end of B, as stated above, and having two recesses on its lower surface to
receive the prongs of the screwdriver; C is a pivot spindle or centre which
fits into the countersunk perforation in the head of the match chamber, and is
secured in this position by the metallic pin D which passes into it through
the walls of the fuze stock. The use of this pin D and its required strength
will be more fully explained hereafter. E is a block of compressed mealed
powder resting on the head of C, and is held firmly down by the screw
plug F in the absence of this powder block, or when it has been consumed;
E represents a space, and when thus referred to will be designated as the
space E; F represents a screw plug in the upper end of the fuse stock, its
central recess and perforations are primed with mealed powder, which lighting
from the flame of the discharge of the gun communicates fire to the powder
block E, which has already been sufficiently described; E represents a
channel formed around the exterior of the striker B, filled with a preparation
of friction match composition; this channel communicates through the
channels O, O, with the orifice U in K; H¹ is a lining of sand paper on
the walls of the match chamber. The channels 0, 0, are filled with rifle
powder, the lower orifice U being properly stopped with wax or some other
suitable substance. Instead, however, of combining all the ingredients of the
friction fuze composition together and placing the mixture in the channel H,
I prefer to place a part of the ingredients on the striker and a part on the
sand paper, thus insuring greater safety.
Having thus described the several parts of my concussion fuze, I will now
explain its practical operation and effects.
It will be observed that I have two expedients for keeping the striker
temporarily in place during firing, viz., first, the pin D, which passes through
both the walls of the fuze stock and the pivot spindle C; second, the block of
compressed powder, which fills the space between the head of the pivot spindle
and the screw plug in the head of the, fuze; the latter is auxiliary to the
former, and in the case of rifle projectiles of a certain description may be dis-
pensed with, as will appear hereafter; the pin D is never dispensed with.
The powder block E which may be described as an auxiliary bolder performs

page_text: he function so long as it remains unconsumed after firing, and if it so
emains until the shell has passed out of the gun its function is accomplished,
t is therefore so made as not to vary much from one second in its time of
ourning. It will be seen that the explosion of a charged shell provided with
bis fuze must take place whenever the plunger being liberated from its axial
bearings comes in contact with the lined walls of the chamber in which it is
placed. The time for the explosion is when the shell strikes its object, the
striker must therefore be so secured that it will become forcibly liberated only
upon the shell striking its object.
Now there are three forces to which the fired shell is subject, any one of which
may if not properly guarded against cause it to explode prematurely, viz.,
first, the shock of the displacement when the shell starts from its seat in the
gun; second, the jumping or rebounding of the shell against the walls of the
gun in passing out of it; third, the centrifugal force due to the rotation of
the shell in its flight through the air. I guard against the first of the said
disarranging forces by fixing the bearing points of the striker in a line
coincident with the axis of the fuze stock, and by making its rear support an
immovable one. If the shell is properly loaded in the gun, viz., with the
axis of its fuse bole coincident with the axis of the bore, it will be seen that
the shock of displacement, so called, will have but little if any tendency to
liberate the striker. The second disarranging force will vary according to
the windage, so called, of the projectile, and will be greater in spherical than
in elongated projectiles; in. the latter case when a good expanding projectile
is used it may be regarded as comparatively a slight force, and one which will
be effectually guarded against by the pin D alone, hence the powder block
when used in this class of projectiles may be removed from the fuze before
placing the projectile in the gun. In the case of spberical projectiles and
mechanically fitting rifle projectiles of considerable windage the powder block
should be used, and is sufficient in connection with the pin aforesaid to
prevent the premature liberation of the carrier and consequent explosion. In
respect to the third-named disarranging force it will scarcely be present in
rifle projectiles upon which the rifle motion has been fitly impressed before
leaving the gun; but in the case of spherical projectiles, more especially those
of large diameters, and in the case of rifle shells when axial rotation is lost or
5 is imperfect this danger is present, and is effectually guarded against in these
extreme cases by the use of the pin D, as in the absence of the powder block
the pin D offers the only resistance to the liberation of the striker or plunger;
it will be understood that a light or heavy shock will be required to liberate
the plunger or striker as the pin D is small or large, so that by regulating the

page_text: size of the pin D I really regulate the fuze, that is, I can so arrange it that
it will ignite by a light or beavy shock, as, for instance, for sea coast and
naval purposes it may be made to explode on striking a wooden ship, but not
to explode on striking the water in ricochet firing; again when to be used in
the field it can be made to explode if desired on striking the ground in
ricochet.
I am aware that fuzes are used which are provided with a movable plunger
in connection with a percussion cap, or some equivalent device for producing
fire by impact or friction, and which are operated by the force of the forward
motion of the plunger in the fuze stock arising from its inertia when the shell
is arrested on striking its object. These fuses depend upon the shells striking
front end on to secure the required forward motion of the plunger, they are
for this reason in strictness called percussion fuzes, and can only be used in
rifle shells; which alone have the required polarity.
Although my fuze resembles that class of fuzes that have a movable plunger
in connection with a fulminate or friction match composition for producing an
explosion when the shell strikes, yet it is quite different in its construction and
mode of action; and may be regarded as an improvement on any of that class,
inasmuch as it operates equally well whether the shell strikes "fuze end on,"
perpendicularly, or obliquely to the axis of the fuze stock, it can therefore be
used in both spherical and rifle shells, and in the latter when fired at the
bighest elevations.
.
Having thus described my Invention, what I claim as new and desire to
secure by Letters Patent is,-
First. A plunger or striker centrally suspended in the fuze case, substantially
'as described.
Second. A plunger or striker supported by conical bearings (in the line of
its longitudinal axis) in such a way that a lateral movement of the plunger
will generate a force acting in the line of its axis on the principle of the wedge
or inclined plane.
Third I claim a movable pivot spindle C with its cross pin D in com-
bination with a fuze plunger or striker, for the purpose of keeping said
plunger in its normal position until the shell strikes.
Fourth. I claim a powder block to be lighted at the instant of discharge,
and to be quickly consumed, to operate as a temporary holder of the movable
apparatus of a fuze intended to ignite by friction on the shell's striking.
Fifth. I claim in combination with the movable spindle aforesaid and a
fuze plunger or striker the powder block, arranged and to operate substantially
in the manner described.

page_text: Sixth. I claim in combination with the movable spindle the set-screw S, or
its equivalent, substantially as and for the purpose set forth.
In witness whereof, I have hereunto set my hand and seal, this Sixth
day of August, A.D. 1867. -
EDWARD AUGUSTUS DANA. (L.S.)