IMPROVEMENTS IN WAR ROCKETS AND IN THE METHODS AND APPARATUS FOR APPLYING THE POWERS OF ROCKETS FOR THE PURPOSE OF OBTAINING COMMUNICATION WITH VESSELS WHICH ARE STRANDED, OR IN ANY OTHER SITUATIONS OF DANGER; ALSO, AN IMPROVED INSTRUMENT AND METHOD FOR ACCURATELY POINTING MORTARS FOR THROWING SHELLS, WHICH MAY LIKEWISE BE USED FOR FIRING SHOT FROM MORTARS, FOR THE PURPOSE OF OBTAINING COMMUNICATION WITH SHIPS
Year: 1838

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
DENNETT, of New Village, in the Isle of Wight, in the County of
Hants, Engineer and Surveyor, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria,
by Her Letters Patent under the Great Seal of Great Britain, bear-
ing date at Westminster, the Second day of August, in the second
year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said John Dennett, Her especial licence, full
power, sole privilege and authority, that I, the said John Dennett,
my exors, admors, and assigns, or such others as I, the said John
Dennett, my exors, admors, or assigns, should at any time agree
with, and no others, from time to time and at all times during the
term of years therein expressed, should and lawfully might make,
use, exercise, and vend, within England, Wales, and the Town of
Berwick upon Tweed, and in all the British Plantations abroad, my
Invention of "IMPROVEMENTS IN WAR ROCKETS AND IN THE METHODS AND
APPARATUS FOR APPLYING THE POWERS OF ROCKETS FOR THE PURPOSE OF
OBTAINING COMMUNICATION WITH VESSELS WHICH ARE STRANDED, OR IN ANY
OTHER SITUATIONS OF DANGER; ALSO, AN IMPROVED INSTRUMENT AND METHOD
FOR ACCURATELY POINTING MORTARS FOR THROWING SHELLS, WHICH MAY
LIKEWISE BE USED FOR FIRING SHOT FROM MORTARS, FOR THE PURPOSE OF
OBTAINING COMMUNICATION WITH SHIPS," in which said Letters Patent is
contained a proviso that I, the said John Dennett, shall cause a par-
ticular description of the nature of my said Invention, and in what
manner the same is to be perforined, to be inrolled in Her said

page_text: Majesty's High Court of Chancery within six calendar months next
and immediately after the date of the said in part recited Letters
Patent, as in and by the same, reference being thereunto had, will
more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso I, the
said John Dennett, do hereby declare that the nature of my said
Invention, and the manner in which the same is to be performed, are
particularly described and ascertained in and by the following de-
scription thereof, reference being had to the Drawings hereunto an-
nexed, and to the figures and letters marked thereon (that is to say):
Rockets as they are now manufactured for military purposes are
generally constructed to burst their shells at given distances, as
nine hundred, one thousand two hundred, or one thousand five
hundred yards, &c., according to the calibre, and they cannot be
altered in the field to adapt them to any other ranges; therefore, if
a rocket constructed to explode at one thousand two hundred yards
be fired at a body of men or other object posted at one thousand four
hundred yards distance, the shell will explode before it reaches
them, and consequently render such fire useless; or if the object be
at a less distance than one thousand two hundred yards, say one
thousand yards, it is obvious that the rocket would pass beyond
before the shell bursts, and the effect of the explosion be equally lost.
The object of my first improvement is to render rockets of my
calibre more effective by causing their united powers of penetration
and explosion to be made available at all distances within their
extreme range, by bursting their shells at the moment of impact or
any object against which they may be fired; and this I accomplish
by means of percussion fuzes of a peculiar construction, which are
screwed into fuze holes tapped to receive them at the apex of the
shells. These fuzes are made of copper, gun metal, or other fit material, a
and have a shoulder on which is cut a male screw to fit the fuze
holes and a flange or rim above it, on which it screws down firmly
upon the shell. The body or shank is bored down to within about a
quarter of an inch of the end, and this bottom or solid part is perfo-
rated with a smaller hole, into which is screwed a projecting piece or 3
nipple, which receives a percussion cap nearly similar to those used
2

page_text: for fowling pieces. A plunger of iron, hard gun metal, or other fit
material, is accurately fitted into the bore, and of sufficient length
to reach below the top of the cap; its upper end is made with
a broad strong head; underneath this head is fitted a collar of cloth,
felt, or other elastic substance, of sufficient thickness to prevent the
plunger from touching the cap when it is put into the fuze, which
should not be done till the rocket is prepared for firing. This col-
lar is to prevent the plunger from being pushed with violence down
upon the cap, and secures it against the danger of accidental explosion,
but from the elastic nature of the materials it will not prevent it from
being driven down and exploding the cap when it strikes an object
against which it is fired. The several parts may be understood by
reference to the Drawing No. 1.
I construct some rockets in a different manner. Instead of a nip-
ple and
cap I make the bottom of the bore convex, and perforate it
with one or more holes. In the bottom of the plunger is made a
shallow cavity which is primed with the detonating composition,
which explodes on being driven down upon the convex bottom. In
either case a small flat must be made on one side of the plunger, to
allow the air to escape when it is pushed into the fuze. As another
variation I construct some without a plunger; these are made with
a strong neck or nipple projecting above the flange on the outside
of the shell, and on which a percussion cap of larger dimensions is
fixed. The parts below the cap are primed and perforated in the
same manner as a priming tube for a piece of ordinance.
My next improvement is intended to increase the destructive
effects of rockets, and to dispense with the pole or stick which is at
present always attached to them. Instead of the pole, I substitute
a short iron bar or rod, either solid or tubular, which screws into
the centre of the rocket in the same manner as does the socket of the
pole. To the other end of this bar or tube, I attach a counterpoise
of metal or other substance, of such form and weight as circum-
stances require. Some I make hollow, of wrought or cast iron, of
cylindrical or other forms, and these I charge with gunpowder,-
carcass composition, case shot, or combinations of them or of other

page_text: combustible or explosive materials, which powder or compositions
are to be fired by fuzes which ignite by the fire from the vent of
the rocket, and may be calculated to burn till after the rocket itself is
expended. By such means, in addition to the ordinary powers
of penetration, explosion, &c. which rockets possess, I obtain a
subsequent power of explosion and conflagration.
To prevent the counterpoises from becoming heated by the fire
from the rocket, and thereby endangering the ignition of the pow-
der, &c. within them, I place a conical guard or shield of iron a
small distance above them, which prevents the fire of the rocket
from impigning upon them. Through this guard or shield the head
of the fuze must project, which being primed and quick-matched in
the usual manner, will insure its ignition when the rocket is fired.
I sometimes also fix in the outside of the rocket case certain ribs
or projections of metal in a spiral direction, so as to cause it to
rotate on its axis during the time of its flight, which tends, in
certain circumstances, to preserve a greater accuracy in its direc
tion. For case shot counterpoises, the case may be cylindrical,
of strong sheet iron, with the lower end, or that farthest from the
rocket, left open. In the upper end, or in a small chamber within it,
I place a charge of powder, and over that a good strong wad of felt,
leather, wood, or other fit substance, which must be closely fitted
round the edge. On this I place in layers as many musket or pis-
tol balls or buck shot (according to the size of the rocket) as will
nearly fill it, putting sawdust between the layers so as to fill the
interstices between them. I then close the cylinder with a good plug
of wood driven down close upon the balls; or I place in the larger
case several small cylinders, each loaded with powder and one or more
balls, the whole of which will be fired by a small portion of power
communicating with the fuze and their respective vents. It is
obvious that such rockets fired amongst bodies of men or horses
must create great distruction and confusion; for after the rocket has
produced its effect, and bursted the shell on its head, a volly of balls
will be fired amongst them from the other end, in whatever direc-
tion it may point. These counterpoises screw on, so that either

page_text: kind (ready charged) may be attached to the rocket during an
action to suit the circumstances of the required service.
The arrangement of the several parts may be understood by refer-
ence to the Drawing No. 2.
My next object relates to improvements for the extension of my
system of applying the power of rockets for saving lives from
shipwreck, by enabling the crew of a vessel at sea to take out the
crew of another which is water-logged or otherwise in danger of
foundering, in which state they are so frequently fallen in with; and
from the great difficulty and sometimes impossibility of relieving
them by the means at present resorted to, they are too often neces-
sarily abandoned to their fate, and the people left to perish after the
most dreadful and protracted sufferings. The object of rescuing my
fellow creatures from this most horrible of all descriptions of wreck to
which the seaman, in his innumerable dangers, is exposed, (though
its appalling circumstances which often place him beyond the reach
of human aid are not witnessed by the eye of benevolence on shore,
and consequently are not so generally understood and provided
against as those which happen upon our coast,) I endeavour to ac-
complish as follows:-The vessel intending to render assistance,
having taken the most eligible position to leeward of the wreck,
and obtained a communication by means of a rocket and apparatus
which I have previously invented, and which are well known, for the
use of ships, she then, by means of the rocket line, sends on board a
self-inflating life slings which I have invented for the purpose, to
which is previously bent a rope running through a tail block lashed
to the yard arm, and through a leading block near the deck. A guy
is also bent to the one of the thimbles at the lower part, and when
hauled on board the wreck another guy is bent to it instead of the
rocket line. It is then ready to be alternately hauled from one
vessel to the other. Into these slings a man places himself, sitting
astride the seat which crosses them, and then on giving a signal
with his hand comes overboard, when he will be immediately hoisted
on board the other vessel by the whip fall at the yard arm.
in the slings he is perfectly secure, he can neither sink nor be washed
When

page_text: out of them, and is quite protected from injury should he chance
to swing against the side or rigging whilst being hoisted in. These
self-inflating life slings are constructed in the following manner:-I
take three strong hoops like mast hoops, large enough for a stout man
to pass easily through them; across one of these I fix a narrow board
which forms a seat, the upper side of which I pad with cork shav-
ings and canvass; I then connect them firmly together with white
rope, the ends of which are spliced together to form double slings
which cross underneath the seat, and to the four parts of rope, the
hoops are then securely seized at the necessary distance apart. In
the two bights of the rope above the hoops is seized a large brass
thimble, to which the whip fall bends for hoisting. Two other
thimbles are also fixed by straps on the opposite sides of the lower
hoop, to which the guys are to be bent when in use. On the out-
side of the frame of hoops is securely fixed an air vessel, composed
of canvass or other material rendered perfectly air and water tight
by a solution of caoutchouc, or other fit waterproof composition.
It may be made of various forms, but perhaps the most eligible is
that of a short cylinder terminating at bottom by a truncated cone.
Two or three narrow hoops are securely fixed inside of the outer
coat of the cylindrical part to keep its circumference extended. In
the upper end of this cylinder is fixed a short stop cock of largish
bore, the plug of which may screw in or turn in the ordinary man-
ner. It is evident that when not in use the machine may be com-
pressed so as to bring the hoops close together, and it will then be
nearly flat, and will occupy but very little room. Now, supposing
it to be in this condition, with the stop cock open: if we gradually
extend it to its full dimensions by pulling at the opposite ends, the
pressure of the atmosphere will cause the air to rush in through the
opening of the cock until it completely fills the space within. The
stop cock being then turned will securely retain it. By this simple
operation it becomes self-inflated, and capable of floating a very con-
siderable weight. But in case it be desirable to obtain a higher
degree of inflation, I attach a small force pump or injector, which is
a small cylinder formed of the same material as the air yessel itself:

page_text: the circumference of this cylinder or pump is kept extended by a spiral
wire or series of small hoops, whilst it is capable of being compressed
and extended in the direction of its length. The top and bottom of
this cylinder are formed of wood or other fit material, in each of which
is an air-tight valve opening inwards, and closed by a slight spring,
and across the top is attached a handle. By briskly working this
cylinder, or in other words extending and contracting it in the
direction of its length, more air may be forced in.
These self-inflating life slings may also be used with great advan-
tage for conveying the people to the shore from a stranded ship
when suspended to a block traversing on an hawser, for which pur-
pose they will be infinitely more safe and convenient than a cot or
any other apparatus at present in use. They may also be used with
equal advantage in rescuing the people from a vessel wrecked at the
foot of a perpendicular cliff, as Portland, Freshwater, &c., when
attached to a cliff gin, which I have contrived for that purpose.
This is represented in the Drawing No. 3.
My next improvements is to enable persons in either of the cases
above mentioned to use a combination of rocket power, by which
means the line may be carried out to a much greater distance than
usual, or a much larger line be conveyed if circumstances require
it, and this without making any, change or alterations in the appara-
tus previously supplied, which I consider an object of great impor-
tance, as ships and stations already equipped can immediately avail
themselves of the advantages which it offers, at a very trivial ex-
pence. This I accomplish by connecting the rockets together by
means of shackles or clamps of iron, which go on over the rockets
and secure with screws. One of these fixes round the rockets at the
lower ends close to the vents, and another immediately above the
upper ends of the poles. In the upper one is fixed a wood
chock or saddle with semi-circular ends, which form a seat for that
part of the rockets, and supports them firmly at the distance re-
quired by the intervention of the poles. This chock is fixed to the
iron clamp only at one side, which leaves the clamp at liberty to
spring open when the screw is slackened, which renders it easily to

page_text: be slipped on or off over the ends of the rockets. One or more clamps
of a smaller size are slipped I on over the poles; and screwed fast to keep
them together in the proper position. In order that the two rockets
may ignite at the same instant by the priming of the lock of the
rocket frame, I connect their vents by a leader composed of several
strands of cotton or worsted quick match, which leader is covered
with a tube of cloth rendered waterproof by a solution of caoutchouc
or other composition. Each end of this leader is fixed to a cross of
copper or brass, two arms of which are bent at right angles, so as to
enter the vent of the rocket into which they are pushed, and by their
elasticity they expand and retain the leader in its position. The
other two arms reach across the vent, and form stops to prevent it
being pushed into the rocket too far. The ends of the leader go
through the centres of these spring crosses, and project about an
inch into the vents of the rockets. To the centre of this leader is
attached another limb of the same description, long enough to reach
into the pan of the lock, and this end being well primed will ignite
by the sparks, and convey the fire simultaneously to both rockets.
These arrangements are explained in Drawing No. 4.
My next is an Invention of an instrument for accurately pointing
mortars by a line correctly coincident with the axis of the bore,
instead of lines temporarily chalked upon the outside of the mortar,
as is now practised, by which the errors arising from any difference
in the thickness of metal, or, in other words, want of concentricity
between the axes of the interior and exterior surfaces of the metal,
will be obviated. This instrument may be made of brass or other
metal, or partly of wood and metal. It consists of a stem or main
piece, which must be two or three feet longer than the mortar, and
worked perfecly true with its sides parallel to each other, and of
equal thickness, which must be sufficient to prevent any tendency to
bend by its own weight. On the upper surface of this piece a middle
line is correctly marked through its whole length. An opening
is cut through this piece from the upper end about two thirds its
length, and in this opening is strained a silk cord or fine wire;
correctly coinciding with the middle line above mentioned. Across

page_text: the
upper surface of this piece are fitted two other pieces correctly
at right angles with it, and their centres exactly coinciding with
the middle line, their length being about one eighth of an inch less
than the diameter of the bore of the mortar with which it is to
be used. These pieces slide up and down on the stem to adjust the
distance between them to the length of the bore, and they screw
fast by milled heads on the under side. To the upper one is
attached a spirit level, by which it may be placed level. On the
lower one, or on the end of the stem, is fixed a weight sufficient to
prevent the other end from preponderating when it is placed in the
mortar. If the instrument be placed in the bore of the mortar, with
its upper surface level across or in the direction of the trunions of the
mortar, the cross pieces resting on the surface of the bore, and the
long arm with the opening in it projecting beyond the face of the
piece, the wire or cord in it will accurately correspond with the axis
of the bore, and form a prolongation of it in that direction, whatever
be the form or imperfections of the outside. Things being thus
arranged, if two pickets be driven into the ground in the direction
of the object to be fired at, and a fine line strained between them,
passing over the mortar (in the manner practised in the French
service), and the mortar traversed till the wire in the instrument
coincides with this line, the bore of the mortar will be correctly
pointed for the object. On the under side of the outer end of the
long arm or stem is fixed a small quadrant or semi-circle, accurately
graduated with a small spirit level turning on its centre, and carry-
ing an arın or index, by which the elevation of the bore is determined.
Instead of a spirit level a silk cord may be suspended from the centre
with a plummet at the lower end, the silk will then cut the angle of
elevation. The plummet and part of the cord should be immersed
in a vessel of water or other fluid to prevent its vibrating by the
action of the wind. When the plummet is used, if the mortar is
traversed till the wire in the stem, the pendulum, and the object be
seen in the same plane, the pointing is correct. In this case the
line and pickets will not be necessary, but may all be used together
if preferred. This is explained by the Drawing No. 5.

page_text: Having thus described the nature of my Invention, I would
remark that I lay no claim to any of the parts which may have been
before known and in use, and variations may be made in some of the
parts, so long as the principles of my Invention be retained, and
which I have fully explained in this my Specification.
In witness whereof, I, the said John Dennett, have hereunto
set my hand and seal, this Twenty-fifth day of January, in
the year of our Lord One thousand eight hundred and thirty-
nine.