51. The tourbillon is a species of firework very ingeniously contrived
to represent a spiral column of fire. Its performance is of short
duration, but while it lasts it produces a very striking effect, and is,
moreover, entirely different from any other pyrotechnic piece.
[Illustration:
Fig. 82.—Block to receive the tourbillon while it is being bored.
_m_—Groove in it to receive the quick-match. Fig. 83.—Block, with
settle (_n_) over which tourbillons are rammed. _Q Q Q Q_—Wooden
cylinder to enclose tourbillon case. _O O O O_—Iron rings to tighten
cylinder. _P P_—Pin to pass through cylinder, and settle to connect
them. Fig. 84.—Tourbillon complete, with stick attached. Fig.
85.—Revolving cradle from which tourbillons are fired. _s_—Iron
spike, with tubular top, in which the cradle revolves. Fig.
86.—Metal tourbillon scale.
]
The preparation of tourbillons requires a considerable degree of nicety
and precision, for unless the several proportions of the piece be
accurately preserved, the true and intended effect will certainly be
lost, and the operator not merely lose a feature, but a very beautiful
feature, in his exhibition.
Since, then, it is utterly impossible to prepare successful tourbillons
by careless manipulation, and to hurry over any part of their
manufacture without some deterioration to their performance, I must beg
that my readers will carefully follow my directions in every particular.
They will then be able to make these tourbillons as successfully as I
do. But if they prefer to work out some principle of their own, they
must not hold me responsible for its results.
For the benefit of those of my readers who may know little or nothing of
what a tourbillon is, I will first endeavour to explain the principle
upon which it is constructed, and then give in detail the various
operations necessary for its completion.
A tourbillon consists of a stout case filled with a strong sparkling
composition, and closed very tightly at both ends. In this case are
bored four holes, at which the fire is to find vent. Two of these holes
are made underneath the case; from these the fire issues in a downward
direction, and gives the piece the power of ascending perpendicularly.
The other two holes are made in opposite sides of the case near each
end; the fire issuing from these causes the case to revolve in a
horizontal direction while it is ascending.
Now, it will be obvious that to gain an exact counterbalancing of these
two forces considerable care and precision will be necessary. In order
to make my directions as clear as possible, I intend to speak only of
one size of tourbillon. You may make them of any size, from the 1-oz. up
to the ½-lb. size, if you please; but you will find it by far the most
_economical_ and _certain_ plan to keep to one effective size, and thus
avoid all confusion and expense arising from the multiplication of tools
and measurements.
We must first of all know how to make the cases. These are to be _of the
quarter-pound size_. You will derive little advantage from adopting a
larger size than this, and you will find smaller sizes unworthy of such
an exhibition as I trust you will be able to make by following my
directions in these papers.
From each sheet of your 70-lb. brown paper you will only be able to cut
two strips of sufficient width and length to make the ¼lb. tourbillon
cases. These two strips are represented at _A_ and _B_ in the annexed
diagram (fig. 80). _These strips must be eight inches wide._ Your sheets
of paper measure about twenty-two inches on their short side; so that if
_A_ and _B_ are eight inches wide, the remaining strip _C_ will be only
_six_ inches wide, and useless, therefore, for tourbillon cases of our
present size. But these spare strips are sure to prove useful for some
purposes, and so no waste will be incurred.
[Illustration:
Fig. 80.
]
The imperial board for these cases must be cut as in the adjoining
illustration. Each sheet of board will provide four strips of a size
proper for our purpose, each of which will be eight inches wide and
fourteen inches long. Those marked _a_ _b_ _c_ _d_ are intended to
represent the pieces to be used (fig. 81). Those marked _e_ _e_ should
be kept with the spare strip marked _C_ in fig. 80, and will make you a
good ¼lb. case for Chinese fire.
[Illustration:
Fig. 81.
]
I will now suppose you to have divided your paper according to the above
directions. In the next place you must paste both paper and board all
over thoroughly. Brush some paste upon your ¼lb former (the one used for
making rocket-cases, which is three-quarters of an inch in diameter),
and then roll on your paper and board in the manner described at p. 77.
Especial care must be taken that the innermost end of the strip of paper
(that which lies next to the former) is so thoroughly saturated with
paste that it cannot become separated or loose. If this precaution be
not taken, some of the composition will, in the process of filling,
drift behind it—will form a quick-match, as it were, inside your case,
and will infallibly cause the tourbillon over which you have otherwise
taken so much pains to vanish in a neat sharp report, and you will
discover to your annoyance that in the place of a tourbillon you have
only made an inferior kind of marroon.
Well, your cases are now made, and are eight inches in length, and
three-quarters of an inch in their bore. Their external diameter will be
found to be about one inch and an eighth.
We must next speak of the composition proper for filling tourbillons.
For this purpose I employ the following formulæ, which I think will be
found to answer well:—
No. 1.
FOR PLAIN
TOURBILLONS.
Nitre 8 parts.
Meal-powder 16 „
Sulphur 4 „
Charcoal 4 „
The charcoal that I use in making up this formula is the same that I
recommended for rocket purposes—that is, it should be partly fine and
partly coarse. If the above composition be found too strong, more
charcoal may be added until the desired strength be gained.
No. 2.
FOR BRILLIANT TOURBILLONS.
Meal-powder 16 parts.
Nitre 8 „
Sulphur 3 to 4 „
Charcoal (fine) 3 „
Steel filings 6 „
The effect produced by this composition is very good indeed, and in my
hands leaves nothing to be desired. It is advisable not to fill the
cases with composition No. 2 longer than necessary before use, as the
steel is sure to become corroded to some extent, and then much of the
brilliancy of the sparks is lost.
Some pyrotechnists use _iron borings_ instead of steel filings for
tourbillons. I cannot say that I have ever succeeded well with them.
Iron particles will not work well in rapidly-revolving pieces, as far as
my experience goes. They seem to me to become chilled too soon by their
motion through the air, and produce hardly any scintillation. I,
therefore, always use steel filings for all fireworks which are intended
to revolve, and employ iron only in those that are stationary. Now,
having prepared your composition, you will be ready to ram it into your
cases. For this purpose you will require a simple piece of apparatus,
which Mr. Newman will make for you at a small cost. You will find a
drawing of it on my page of illustrations (fig. 83). It consists of a
block of wood provided with a “settle,” on which one end of the
tourbillon case is placed, and over which the composition is rammed.
Then there is a wooden mould capable of inclosing the case and
supporting it tightly and firmly while the operation of ramming is being
performed. This mould consists of a hollow cylinder of wood pierced
throughout, and of such a size in its bore as will just admit the
tourbillon case. The mould is divided longitudinally in halves, and
these halves are kept together by means of iron rings, which encircle
the whole. You will find a full description given with the drawing.
In order to fill the cases, squeeze one end of one of them over the
projecting piece at the top of the settle. Then fit on the two halves of
the cylindrical mould, and drive down the iron rings until they are
tight. The exterior of the cylinder is made to _taper_, in order that
the rings may always fit tightly over it. And, lastly, put in the pin
which secures the cylinder to the block and settle. You will now require
a straight wooden drift, eight inches long (independently of its
handle), and nearly three-quarters of an inch in diameter—one, in fact,
that will pass _easily_ into your tourbillon case. The tools you have
already—viz., a scoop for the composition, a mallet, and the short
_solid_ drift which you used for driving in the clay over the
composition in your quarter-pound rockets. First put into your
tourbillon case as much clay as will, when rammed very hard, occupy
_three-eighths of an inch in the length of the case_. The settle
projects into the case about one-eighth of an inch, and thus
half-an-inch at each end of the case is left for the purpose of insuring
a very firm ending, which cannot be blown out by the combustion of the
composition.
When the clay has been rammed in as tightly as possible, drive in the
composition, a ladleful at a time, as uniformly as you can, until you
have only half-an-inch at the upper end of the case unoccupied by it.
Into this vacant space drive the same quantity of clay that you put into
the lower end, and be sure that it is rammed in very firmly indeed.
The ramming of your tourbillon is now completed, but the most important
part of its manufacture has yet to come. Open your penknife, and lay its
blade on the table, back downwards and edge upwards. Place your filled
tourbillon case across the edge of the knife, and _find the exact
central point at which it balances on it, and mark that point by making
a hole there with a small bradawl_. Now, having found the centre of its
balance, you have next to mark the places at which the holes are to be
made, and by far the best way to save yourself trouble in this respect,
and to insure the proper marking out of all your tourbillons, is to
follow my plan, which I am now about to describe. At fig. 86 I have
drawn out for you a shape which you must get copied exactly in tin or
zinc sheet. This piece of sheet metal, _when bent into the form of a
trough of such a size as to fit tightly round your tourbillon case_,
will give you the true position of the holes. In using it you will have
to put the filled tourbillon case into it, and make pencil marks through
the holes that correspond to those drawn in my sketch, and you will then
have got over the entire difficulty. In the middle of the scale which I
have drawn is one small hole marked _H_. _This hole is to come exactly
over the mark which you made with your bradawl at the balancing point_,
and if this be done all the rest must come right.
Having thus marked the position of the holes, the next thing is to bore
them. They should be as nearly as possible three-sixteenths of an inch
in size. I use a large bradawl for boring the holes, and it is better to
drive it into the case with a mallet than to work it in with the hand.
It must not be driven in farther than necessary, the object being merely
to make a clear hole through the case, and not to disturb the
composition. If you drive in the bradawl with your mallet you will
require a small block of wood with a groove cut in it, in which you can
lay the case while making the holes. I have given you a sketch of such a
block at fig. 82. If it is two inches square or rather more it will be
quite large enough. You will find the block very useful afterwards in
attaching the stick to the tourbillon.
The plan that I have given for the _tin or zinc tourbillon scale_, as I
shall call it, is drawn out _quarter size_, and the dimensions, marked,
so that no tinman can have any difficulty in copying it accurately. Your
tourbillon case is 8 inches in length. Half-an-inch at each end is taken
up by the clay endings, so that you have seven inches of composition in
the case. The two extreme holes, _which are on opposite sides of the
case_, are made at the ends of the composition. The fire issuing from
these gives the tourbillon a horizontal revolution round its centre of
balance. The two inner holes, which are on the under side of the case,
should be the same distance from one another that they are from the
extreme holes. The fire issuing from these gives the tourbillon its
ascending power.
But we have now to connect all these holes with quick-match, in order
that the composition may take fire at all the four points
simultaneously. To do this, begin at one of the under holes (those
marked _F_ in the scale), and press into it the end of a piece of
_uncased_ quick-match, taking care that the match reaches the
composition. Then carry the match on to the nearest _side hole, and
press it into it_. Then carry on the quick-match _over the upper side of
the tourbillon_ to the side hole at the other end of the case, and press
it in there; and, lastly, carry it on to the remaining under hole, and
press it into it.
Having completed this operation, cut some strips of thin paper, about an
inch wide, paste them well all over, and cover the quick-match with
them, holes and all. A very little practice will enable you to adapt
this pasted paper very neatly.
The tourbillon, if now ignited, will be sure to go somewhere, but
probably not in the direction which we should like it to take. In order
to regulate its flight we must do as we did with the rockets, adjust a
stick to it, which shall have the effect of keeping its under side
downwards, and so of compelling it to move upwards perpendicularly, if
at all.
This stick is usually made of a curved shape in the manner represented
at _I I_, in fig. 86. Those that I use I get from Mr. Darby; they are
eight inches long, about an eighth of an inch thick, and are made of
beech. There is a small hole in their centre through which a
_flat_-headed nail is driven into the tourbillon at its balance point,
which you marked with your bradawl. The stick must, of course, lie at
right angles with the case in the manner represented at fig. 84. It is a
very good plan to put a drop or two of glue at the point where the stick
touches the case, as it will then be prevented from shifting its
position.
In driving the nail through the stick into the tourbillon, make use of
the block represented at fig. 82, having previously cut at the bottom of
its rounded groove another small groove diagonally, so that when the
tourbillon is lying upside down in the large groove, for the purpose of
having the nail driven into it, the quick-match that extends across it
may lie in the smaller groove, and may not be injured by being crushed,
as would otherwise be the case.
The nails used should be about three-quarters of an inch long, and
should have a smooth, flat head.
To fire the tourbillon, place it stick downwards on a level board, and
see that it spins easily and freely on the head of the nail. Then with a
portfire burn through the quick-match _in the middle on the upper side_.
The tourbillon will make a few revolutions on the board before it begins
to rise.
I have known several tourbillons fail, when I had reason to believe that
there was nothing faulty in their make. They all behaved in the same
unaccountable manner, jumping off the board and falling bottom upwards
upon the ground. Of course, after this freak they could not right
themselves. They appeared to sink into a kind of blustering, sulky fit,
and when exhausted went out. Some time elapsed before I could assign any
satisfactory cause for this remarkable behaviour, but at last I began to
suspect the board on which the tourbillons were placed to fire them. It
occurred to me that there was not room enough for the rush of fire from
the under holes between the tourbillon and the board, that as soon as
the fire had been conveyed to these under holes the force generated then
and there was sufficient to throw the tourbillon over on its back, and
thus effectually to prevent any further performance. Now this was by no
means satisfactory, for if there is any single firework which requires
care, exactness, and attention in its preparation, it is the tourbillon.
I have often felt that I would much rather have a rocket than a
tourbillon, for in the first place the latter takes much longer to make,
and one feels that one should have some remuneration for one’s trouble;
and in the next place a good tourbillon, though it is a species of
firework not by any means so necessary to an exhibition as the rocket,
is still one capable of producing a very unique and grand effect. I
began to suspect that the board was the cause of my failure, and after a
little consideration I came to the conclusions here enumerated:—
1st. That a board of proper size, shape, and level was a thing not
always to be found when one wanted it, particularly if away from home.
2nd. That it was a very lumbering piece of luggage to carry with one
when about to take an exhibition to a distance.
3rd. That, if warped by damp, or put out of its level in any way, it
would be rather worse than useless.
4th. That something better might be contrived.
Whether I was right in blaming the poor board I do not know; but one
thing is certain—that I have never, since the adoption of my new plan,
had any failures at all with tourbillons.
I wanted something from which to fire the tourbillon which would leave
it no excuse for turning on its back, which would be small and portable,
and always ready for use.
I first made a brass cross of the shape and size indicated in fig. 87.
In the ends of the arms I drilled holes, into which I soldered pieces of
stout brass wire about two inches and a-half long. Thus a sort of cradle
was formed like that which is represented at fig. 85 in the plate. The
next thing to be done was to enable the cradle to revolve very easily.
To do this I soldered on to the centre of the under side of the cross a
piece of brass rod of the size generally used for stair-rods. This piece
was about six inches in length, and was filed at its lower extremity to
a point on which it might revolve. I thus had made a thing like that in
fig. 88. Now all that I had to do was to get a piece of glass tubing,
into which my piece of rod at _a a_ would fit easily, and in which it
would turn freely. This I did, and procured also a piece of iron rod
half-an-inch in diameter and about eighteen inches long. I had this
forged into a kind of spike point at its lower end, and filed at its
other end, to pass about an inch into the brass tube, and then I had the
tube and iron spike soldered together. This iron spike I press into the
ground, taking care that it is upright, and then drop the brass rod
which is soldered to the cradle into the brass tube at the top of the
spike. The cradle will be found to revolve freely. In it I lay the
tourbillon, with its stick downwards. When it is fired the holes at its
_sides_ are first ignited, and so its _horizontal_ revolutions begin
before any ascending power is given to it. The cradle of course revolves
with it, and, if properly made, can offer no obstruction of any kind to
its free play. But as soon as the fire is communicated to the _lower_
holes, the force there developed will lift the tourbillon out of the
cradle, and will send it on its upward flight.
My description of this little piece of apparatus may, perhaps, incline
my readers to imagine that its manufacture is difficult. I can only
assure them that it is not so, and that, if they will only give it a
trial, they will be convinced of the advantages which it possesses over
the old plan of the board. Probably some modification of its principle
will occur to you which may render it still more easy to be made. The
means at your own command are, after all, the best referees as to which
is the shortest and readiest method of carrying out any plan. I have
given you the method by which I obviated the difficulty that met me. I
need only add that if you use the board I hope that your tourbillons
will not disappoint you as mine did me.
Many persons make _six_ holes in their tourbillons—four on the under
side, and one at each end or opposite side. For my own part, I never
could see the advantage of this plan. I have tried it and succeeded with
it, but the effect has been always to convince me more firmly of the
superiority of the four-hole system. I know one or two very successful
pyrotechnists whose experiments have led them to the same conclusion.
It is possible to ram tourbillons without a cylindrical mould, but it is
neither advisable nor convenient. The cases require some very
substantial support while they are being filled, for the composition
cannot easily be driven too hard. The cylindrical mould cannot be an
expensive apparatus if made as I have suggested. Mr. Newman has such
facilities for boring blocks of wood and turning them, that I strongly
recommend you to get him to make you one, as it will considerably
lighten the trouble of preparing tourbillons, besides giving them, when
prepared, a much better chance of success.
I beg here to give my readers the size of 70-lb. paper and imperial
board, that there may be no difficulty in knowing what to purchase. The
sheets of 70-lb. brown paper and imperial board are of precisely the
same size, which is 22½ × 29 inches.
I must conclude the subject of tourbillons with one hint. The person who
fires a tourbillon with a portfire will generally fail to get a good
view of its performance. The plan that I commonly adopt is to cut an
inch of quick-match and twist some touch-paper round one end of it, and
lay the other end next to the match on the tourbillon at the point _r_
in fig. 84, pasting a piece of thin paper over it to secure it, and
leaving its other end free, with the touch-paper round it.