4. The first thing that you have to do is to make the case. Do not hurry
over this part of the process, for more depends upon it than is
generally supposed. It is made in the following manner:—Procure some
imperial board (which is a kind of thin pasteboard made of two sheets of
brown paper pasted and pressed together); also some stout Kentish brown
paper of such a substance as will weigh 70-lb. per ream. Now fold a
sheet of the imperial board down the middle of its length, thus:—
Cut it along this fold, then divide each of these halves crossways into
five equal parts and cut them apart. Each sheet will thus furnish enough
board for ten ¼lb. rocket-cases. This board is only made in one size.
Now take a sheet of the 70-lb. brown paper, divide it into halves at its
natural fold, and then divide each of these halves crossways into four
strips. One of these, together with one of the strips of imperial board,
will be sufficient to make one case. I have given you above the
directions for cutting your paper and board without waste; you will,
however, find it more convenient to buy them ready cut up; it will save
you time and trouble, and will occupy much less space among your stores.
They can be procured of Mr. W. H. Darby, 98, Regent Street, Lambeth,
London, and he will supply them ready cut if you only state for what
purpose they are intended.
[Illustration:
2
]
The “former,” on which the board and the paper are to be rolled, is
simply a piece of brass tubing, about 12 in. long, and ¾in. in diameter.
This you had better procure of the person whose name I shall mention
presently, when I speak of apparatus, and to whom I recommend you as a
maker of all pyrotechnic _tools_, except such things as the sieves, &c.,
above mentioned.
I must not speak about the pasting and rolling of the cases until I have
said a few words upon the subject of the paste itself. It is a great
mistake to have your paste made thick; you will gain nothing by doing
so, and you will find it very troublesome to use. It should be made of
such a consistency as will admit of its being spread very readily upon
the brown paper, &c., and by being tolerably fluid will saturate it much
more thoroughly; and this, after all, is what you want to do, for the
hardness of the finished cases depends far more upon the complete
saturation of the paper than upon the thickness of the paste between its
layers. The brush, which you will find convenient, is one about 2in. in
diameter, and can be procured of Mr. Darby. Into each pint of paste,
while boiling, put a large teaspoonful of powdered alum; this will have
the effect of keeping your paste sweet and free from mouldiness for
weeks, and will also prevent it from becoming watery, which it would
otherwise do in a few days.
I will now suppose you to have your paper, imperial board, paste, and
brush ready to hand. You will next require some kind of slab on which to
paste and roll your cases. For this purpose I use one of the largest
common roofing slates that can be procured: its size is 24 by 12in. This
makes a cheap and very serviceable pasting slab if its surface be only
moderately smooth.
Now we come to the actual rolling of the cases. First paste all over one
side of one of the strips of 70-lb. brown paper; then take one of the
strips of imperial board, and fold one end of it once round the brass
tubular “former.” Hold this, thus folded, with your left hand, and paste
over all the rest of the upper side of the strip with your right. Then
roll it up, as straightly and as tightly as you can, till all but about
3 inches of it is wound upon the “former.” Upon these projecting 3
inches lay the end of the strip of brown paper, with its pasted side
upwards, and then roll it till both board and paper are neatly and
closely wound round the “former.” You will find at first a little
difficulty in getting the strips to roll up straight, but a little
practice will overcome this. You will now require what is called a
“rolling board,” that is, a piece of common smooth deal board about 20
inches by 8 in size, with a wooden handle screwed on its upper side at
one end (see fig. 3). Then with the left hand take hold of the end of
the “former,” which projects out of the case, loosely, so as to allow it
to revolve in the hand, and with the right hand roll case and “former”
from one end of the slate slab to the other between it and the rolling
board, pressing upon the latter, and using it as a carpenter does his
“trying plane;” and by this means the same effect will be produced upon
your newly-made case as is produced upon linen, &c., by a mangle. These
directions read, no doubt, as if they belonged to some very complicated
operation; but let me assure you that it is one far easier to perform
than to describe. Some modification of this plan will in all probability
suggest itself to your mind as an improvement upon it; for there are few
people who do not after a few trials fall into some method of working
which, besides answering their purpose, has the additional merit of
being peculiar to themselves. I may as well mention here that the
quickest way of making cases is to paste all your strips of paper and
board before you begin to roll any of them, taking care not to paste
that part of each strip of board which is to make the first turn round
your “former.”
[Illustration:
3.
]
[Illustration:
7
]
In the next place, when you have made as many cases as you require, the
operation of “choking,” or forming their mouth and neck, remains to be
done, and is to be accomplished in the following manner:—Procure some
strong close string about one-eighth of an inch in diameter; take about
one yard of this, and tie one end of it to a ring or nail which has been
driven very tightly about 3 feet from the ground into a wall, beam, or
tree, and the other end of this string tie firmly round a stout piece of
stick or ruler about 18 inches long. Now take the round-ended drift
(fig. 4), and insert this into one end of your cases till its rounded
end appears about an inch from the other end, leaving, in fact, an inch
at one end of the case unoccupied by the drift. Then take the little
“choking piece” (fig. 5), and insert its metal point into the hollow end
of the drift. This operation is illustrated at fig. 6. Now rub your
string well over with yellow soap; the more thoroughly this is done the
better. Then pass the stick or ruler between your legs in such a manner
that by leaning backwards you can make the string very tight; but before
tightening it give the soaped part of the string one turn round the part
of the case marked _e e_ (fig. 6), then by leaning backwards you will
contract that part of the case until you leave an aperture only large
enough to admit the point of the “choking piece.” As soon as this is
done tie some string tightly round the neck thus formed, to prevent its
becoming larger. The best knot for this purpose is the one given at fig.
7. Then, when you have drawn out your choking piece and drift, the
proper name of which latter is “_the setting-down piece_,” your case
must be put by to dry thoroughly before use. The apparatus given at fig.
8 is very convenient for choking cases quickly, and is given in case you
should think it worth while to make such a thing. Any boy with a fair
notion of carpentering would find no difficulty in making it. It is
simply a string passed over a small wheel and fastened to a pedal which
works on a hinge close to the ground. A glance at the diagram will show
you that by putting your foot upon the pedal _f_ the string may be drawn
very tight. The case is choked at the point marked F. No choking can be
done except while the cases are wet.
[Illustration:
9
]
Now, supposing that you can do nothing else until your cases are dry, I
will, meantime, introduce you to some of your tools. Fig. 9 represents
the block and spindle over which your rockets are to be rammed. The case
of the rocket is forced, mouth downwards, over this spindle by inserting
into it the setting-down piece (fig. 4), which you have used before, and
giving the handle of this some blows with the mallet (fig. 10). This
operation has the effect of enlarging the choke to its proper size, and
of making the mouth of the case very smooth and hard. The diagram (fig.
11), represents the steel spindle and nipple in its proper size. The
part marked _g g_ is driven into the wooden block which forms its foot.
Fig. 12 represents the rocket-case driven down upon the nipple when
ready to be filled with its composition. Figs. 13, 14, 15, are three
drifts of different lengths, pierced so as to admit the steel spindle,
and to be used for driving the composition into the cases round the
spindle. They are used in the following manner:—A ladleful of the
composition is put into the case, and then driven down with the longest
of these drifts by the mallet; then another ladleful driven with the
same. Then a shorter drift is taken for the next few ladlefuls; then the
shortest, till the case is full up to the top of the spindle. Then the
unpierced drift (fig. 15) is used to ram in some composition solid, and
to drive some clay upon the top of this. This operation will be
described much more minutely in its proper place. Fig. 17 represents the
“former” on which the cases are rolled.
These tools may be procured at a very reasonable price of Mr. Newman, 4,
Augustus Street, Regent’s Park, London.
Having made you slightly acquainted with the various tools and apparatus
to be used in making and filling rocket-cases, it will now be necessary
for me to say a few words about their size and proportion, for much will
depend upon accuracy in this particular. I have given you a sketch of
four drifts to be used in loading your cases with composition. The
longest of these I shall call _the first_; and the shortest, which is
the solid one, _the fourth_; this being the order in which you will have
to use them. The measurements that I am now about to give have reference
only to _the straight part_ of the drifts, not taking their handles into
consideration. The length of the first drift is 6 inches; second, 4½;
third 3¼; fourth 2¾. The first three of these drifts are pierced or
hollow, in order to admit the steel spindle over which the rocket is
rammed. The first should be pierced to the length of 4 inches; second,
2½; third 1½.
Taking the exterior diameter of ¼ lb. rocket to be about 1 inch—and this
measurement is near enough for our purpose—the former on which the cases
are rolled should be ¾ of an inch in diameter, and the drifts about ¼ of
an inch in diameter. The “former” should always be slightly larger in
diameter than the drifts, because the paper that is rolled upon it is
thoroughly wetted with the paste, and in drying will shrink a little;
and, therefore, if your drifts be of the same size with your former, you
will find considerable difficulty in getting them in and out of your
cases; they ought to be a good easy fit. Twelve inches you will find a
convenient length for your former.
In case you should wish to prepare rockets of other sizes, and in order
that you may readily see the relative magnitude of cases of such sizes
as are generally used in the art of pyrotechny, I here append a
table:—Those which are called
1-oz. cases are about ½ inch bore.
2-oz. „ „ ⅝ „
¼ lb. „ „ ¾ „
½ lb. „ „ 1 „
In following the directions which I gave in my last paper for cutting up
your imperial board and 70-lb. brown paper for rocket-cases, you will
find that the case produced will not be a very stout one. Although I
have made an excellent rocket in a case of such a thickness, you will,
perhaps, find it advisable to use more paper and board, and prepare a
thicker case. For this purpose cut your board in the manner that I have
described before for your 70-lb. brown paper—that is, into _eight_ equal
strips—and then cut each of your sheets of brown paper _lengthwise into
four_ equal strips. By this plan you will be able to make very stout
cases, which will not be at all liable to injury during ramming; and
thus one sheet of board, with two of brown paper, will furnish eight ¼
lb. rocket-cases. You must bear in mind when choking them to contract
the aperture till it is considerably smaller than you will eventually
require it to be. The setting-down piece (fig. 4) has two uses: it is
employed first in choking the case, and afterwards in driving or setting
it down, when choked, over the steel spindle. The reason for driving the
case thus down till the mouth is brought close to the nipple at the foot
of the spindle is that the choke or aperture may thus be left of the
proper size. This proper size is about two-fifths of the inner diameter
of the case; and the aperture left immediately after choking should not
be much more than one-fifth of the same inner diameter. The operation of
“setting down” the cases is performed best, in my opinion, when they are
perfectly dry and immediately before they are filled.