44. You will do well to remember that the remarks that I have already
made, under other heads, concerning _device_ are especially applicable
to the subject of wheels. I am not giving you designs to lead you to
suppose that this or that is _the_ way of accomplishing any one object.
There is no limit to the methods by which you may work out any plan, and
this you will discover by degrees, as your knowledge of the art of
pyrotechny grows riper, and your hands become more dexterous, and your
manipulation consequently more easy.
But in the outset of our subject, let me advise you not to attempt to
make catherine-wheels—that is, those small spiral wheels which are made
by the professionals to sell on the Fifth of November, and seem to be
intended for little girls to fire. You have nothing to do with such
pieces as these. Your object is to provide _an exhibition_, and you will
find it worth your while to bear in mind that the fireworks made by
professionals are of two kinds—those made for their _retail_ business,
which consists for the most part of _small_ single pieces, and which are
papered up very neatly for sale, and those which they prepare for their
large exhibitions, and which are in many instances made in an entirely
different way from the former. Catherine-wheels cannot, as far as I can
see, be employed in combination, and on this account they can form no
part of our present work. I am very ready to allow that, when properly
made, they are very pretty little things, but, not being available for
our immediate purpose, they must be passed over here. In case, however,
any one of my readers may happen to be so prejudiced in their favour
that he cannot consider his exhibition perfect without them, I may as
well say that he can procure them of Mr. Darby quite as economically as
he can make them himself, for the rolling and the filling of their cases
involves an expenditure of time and the acquisition of a certain
“knack,” which, when we consider that the wheel _will only do one thing_
after all, seems like a wilful waste of such perseverance as might be
directed much more profitably to some worthier object.
Now, the wheels of which I am about to treat are such as are made by
tying on choked cases, filled with a strong composition, to frames of
various forms, in such a manner that the recoil of the case during
combustion shall have the effect of driving the wheel. The preparation
of the composition for this purpose, and the making and filling the
cases are exceedingly simple: and, in fact, the only part of
wheel-making which requires any degree of nicety is the preparation of
the woodwork; for, unless the framework of the wheel be tolerably well
balanced, and made to run easily and smoothly on its axis, much of the
intended effect of your piece will be lost.
But we had better begin with the cases and compositions, and then
proceed to consider the various modes of combination in which they can
be employed.
The cases that I use for wheel purposes are of two sizes only—the 2-oz.
and the 1-oz. size; and of these two sizes, the one far most commonly
useful is the 1-oz. Cases of the 2-oz. size are necessary only for large
wheels, where a considerable weight of material has to be set in motion.
I make both these sizes of cases of the same length—that is, about 5½
inches long.
[Illustration:
Fig. 56.
]
[Illustration:
Fig. 57.
]
The paper for the 2-oz. wheel-cases is to be cut as follows:—Divide each
sheet of 70-lb. brown paper into eight equal pieces (see fig. 56), and
then divide each sheet of imperial board into ten equal strips. Then
proceed to make your cases, pasting and rolling them in precisely the
same manner as previously directed, taking especial care that the inner
fold of the paper, which lies next the former, is thoroughly saturated
with paste, so that it is not loose when the former is drawn out of the
case. If this inner edge be left loose, the composition will get behind
it, and, upon firing the case, will act as a quick-match, and infallibly
burst the whole, and destroy your piece, and not only your piece of
pyrotechny, but also your peace of mind; so do not fail to remember this
hint.
Your 1-oz. cases for wheels must be made in the same manner, and with
the same care. But your imperial board must be cut differently. Cut your
70-lb. paper in the same manner as directed above for 2-oz. cases—into
eight equal strips—and your board into pieces of half that size—that is,
into sixteen pieces. These divisions will give you cases quite thick
enough for all purposes. Of course, each case is to consist of one piece
of board and one strip of paper.
You will require no more tools for the filling of these cases than those
already mentioned. The operations of choking and ramming are to be
performed in the same manner as directed for cases of brilliant and
Chinese fire, and the same blocks and nipples are to be employed.
We now come to the compositions with which the cases are to be filled.
For these I give you several formulæ, in order that you may be able to
vary your fires according to taste.
No. 1.
Meal-powder 16 parts.
Steel filings 4 „
This is the brilliant composition given in paragraph 41, which is used
also for wheels with excellent effect.
WHITE FIRE.
No. 2.
Meal-powder 16 parts.
Sulphur 3 „
Or,
No. 3.
Meal-powder 16 parts.
Nitre 4 „
Sulphur 2 „
Charcoal (No. 2) 2 „
Or,
No. 4.
Meal-powder 20 „
Charcoal (No. 2) 4 „
Or,
No. 5.
Meal-powder 16 „
Fine litharge 3 „
Or,
No. 6.
Meal-powder 40 „
Nitre 20 „
Sulphur 4 „
Charcoal 3 „
Bright steel filings 6 „
Litharge 2 „
Or,
No. 7.
Meal-powder 16 „
Nitre 2 „
Sulphur 2 „
Charcoal (No. 2) 2 „
Glass dust 2 „
Of the above compositions, Nos. 1, 2, and 4 will be found the most
generally useful; and of these I prefer No. 4 for all ordinary purposes.
Remember that the compositions for wheel-cases are by far the strongest
that are used in the whole range of pyrotechny, and that they must on
that account be compressed very evenly and completely in the cases, or
they will burn too rapidly, and explode when ignited.
You will find it very advisable to ram a small quantity of the
preparatory composition, recommended in paragraph 40, into the cases
before putting in the wheel-case composition which you have selected.
The cases should be filled till the composition rises to about
half-an-inch from their ends—that is, half-an-inch at the end of the
case should be left unoccupied by the composition. They should be primed
with wetted meal-powder as soon after they are filled as convenient,
care being taken that the space which the point of the nipple occupied
during the operation of ramming is filled up by the priming.
[Illustration:
Fig. 58.
]
When the filling and priming of all your cases is accomplished, you will
next have to cover them with paper which shall project about an inch
beyond each end of the case. The object of this is to enable you to tie
in the quick-match which is to connect one case with another. This
operation is very easily performed. Cut some ordinary newspaper into
strips wide enough to project an inch over each end of your case—that
is, _about eight inches wide_—and long enough to go two or three times
round the case. It will not be necessary to paste the newspaper strips
_all over_. If they are pasted slightly _at each end_ it will be quite
enough. The paste at one end of the strip will stick it to the case, and
that at the other end will fasten it down so as to prevent it from
coming unrolled. The annexed sketch (fig. 58) will show you how the case
ought to be covered.