11. Lastly the rocket-_stick_ remains to be considered. This appendage
is used for the purpose of keeping the mouth of the rocket _downwards_,
so that if it move at all its motion must be an upward one. The rule for
telling whether the stick be of the proper weight or not is the
following:—After having tied it on to the rocket in the manner indicated
in the page of illustrations, ascertain whether it will balance if laid
across the finger about 2 inches from the mouth of the rocket. If the
stick forms an exact counterpoise to the rocket at this point, it will
answer your purpose very well. The length of the stick which I use for
¼lb. rockets is 4 feet, and its size about ⅜ × ½ inch. The best wood for
these sticks is American pine. It is very light, and should be free from
knots. You will be able to procure them much cheaper of Mr. Darby, and
much more uniform in their make, than of any carpenter. In some old
treatises upon pyrotechny you will find recommended a tapering
rocket-stick, to the _large_ end of which the rocket is tied. I have
never found any advantage which these sticks possess over those that are
of one size throughout; and I think I may say that no professional
pyrotechnist uses tapering rocket-sticks. On the annexed page of
woodcuts (figs. 23 to 26) I have given you a sketch of the rings which I
use, through which the rocket-stick must be passed, and from which the
rocket is to be fired. These rings should be screwed into an upright
post (fig. 27) standing 5 feet out of the ground; the upper ring near
the top of the post, the lower about 3 feet from the ground. There is
also a sketch (fig. 28) to show you how the rocket is to be suspended on
this post.
I have stated above that there are _two_ ways of priming rockets; the
one used for exhibition purposes I have already described. Rockets thus
primed are fired by applying a lighted portfire to their mouth. The
other method I have found very convenient when making trials either of
rockets or of stars, for it enables you to get some distance from the
rocket-post before the rocket rises, and consequently to gain a much
better view of the object of your experiment. It is done in the
following manner:—Paste or tie a piece of touch-paper round the mouth of
the rocket which shall project an inch or rather more beyond the mouth.
Then take a piece of uncased quick-match about 2½ inches long, and put
it into the soul of the rocket, leaving so much of it outside the choke
as can be twisted into the projecting part of the touch-paper. If this
is done so as to leave a short twist of touch-paper beyond that part
which contains the quick-match, you will gain a short interval of time
between the moment of lighting the rocket and that of its ascent.
You can procure of Mr. Darby the cases _ready made_, and, in fact,
anything employed in firework manufacture; but I strongly recommend you
to learn to make the cases yourself, as you will then be not only much
more independent, but also much more economical in your work.
Let me recapitulate a little, and add a few hints to remind you of
certain points important in rocket manufacture.
Do not hurry over any part of the work, either the making the cases or
the composition, or the ramming of the rockets.
In moistening your composition with spirits of wine or gin, be careful
to add very little of the liquid, and to stir the composition about
_very thoroughly_ until all the moisture that is present is very equally
diffused.
Remember that the addition of nitre or meal-powder to your composition
will render it more rapid in combustion; the addition of sulphur or
charcoal more slow. By this means you can vary the strength of your
rocket composition to any degree which proves successful or satisfactory
in your hands.
By no means forget to bore a hole through the clay at the end of your
rocket, and thus to form the communication with your stars.
Never allow your steel spindle to become rusty. Every coat of rust that
you have to scour off from it diminishes the size of the spindle.
Remember that the work that is done neatest is always done best.
ROCKET STARS (How to Make).
12. By following a few simple directions for the manufacturing of these,
you will be able to vary almost to any extent the heads of your rockets,
and to produce combinations according to your taste and fancy.
The stars that are used as decorations to the different species of
fireworks are of various kinds, sizes and shapes, according to the
purpose for which they are intended.
1st. The ordinary rocket stars, which are called “brilliant” or
“bright,” are made in small cubes. Their composition is moistened with
gum-water, and while moist flattened to the thickness required. It is
then scored or cut across with a knife, and allowed to dry. When dry it
can be easily broken up into cubes at the places where it was divided by
the knife. _Tailed_ stars are also made in the same way and of the same
size.
2nd. Roman candle stars are small cylinders of composition made of a
size proportioned to that of the case out of which they are to be
thrown.
3rd. _Coloured_ rocket stars are made by driving the coloured
composition, slightly moistened, into small cases, which go under the
name of _pill-box cases_. If the star is to consist of one colour only,
these pill-boxes are open at both ends, and a piece of quick-match is
placed between the composition and the inside of the pill-box, and
allowed to project about half-an-inch beyond each end of it. When fired,
these stars burn at both ends at the same time, and so produce a great
amount of fire in proportion to their size.
If it is required to make stars consisting of more than one colour (in
which case they are called “changeable stars”), the pill-boxes are left
open at one end only. The composition is thereby prevented from burning
at more than one of its surfaces at a time. These stars generally
contain _two_ colours; the pill-boxes are half-filled with one coloured
composition and the remaining space filled with another. These
changeable stars burn much longer than the others, and therefore produce
a more beautiful effect; but being larger they require to be used in
larger rockets, the _half-pound_ size being the smallest that is adapted
for this purpose.