Part 10
No. 23. Chlorate of potash 84 parts. Nitrate of strontia 80 „ Calomel 51 „ Dextrine 22 „ Shellac 18 „ Chertier’s copper 4 „
Of these two formulæ, No. 22 is the one that I generally employ. It produces a very brilliant colour, which is _almost scarlet_, and forms, in my opinion, the best contrast both to the green and purple lights. No. 23 gives a deep rich crimson, which may also be found very effective occasionally. Dextrine, which enters into its composition, is always to be had in very fine powder, and therefore it will give you no trouble to bring it into the proper condition for use. It is very cheap, being sold generally at from 1s. to 1s. 6d. per pound. You will require only a very small quantity of it.
We now come to the last of our colours for making these decorating lights, and that is the purple.
_Purple._ No. 24. Chlorate of potash. 28 parts. Chertier’s copper 28 „ Calomel 13 „ Shellac 8 „ Stearine 1 part.
Or,
No. 25. Chlorate of potash 40 parts. Calomel 28 „ Chertier’s copper 28 „ Dextrine 10 „ Stearine 3 „
No. 26. Chlorate of potash 26 „ Chertier’s copper 24 „ Calomel 14 „ Shellac 7 „
All of these three formulæ produce good colours. I think that I am rather inclined to give the preference to No. 25, on account of the very effective contrast that it makes when employed to burn with the red at No. 22. These three colours are perfectly safe, for the same reason that I stated above when speaking of the red lights.
I trust that the formulæ which I have now given will be found to supply all that you will require in this department of pyrotechny. The compositions have all been used by me, and I can therefore speak from actual experience of their respective merits, and so you will be pleased to remember that if they do not succeed in your hands the fault will lie either in the condition, perhaps the impurity, of your chemicals, or in your own manipulation. I can answer for the receipts; all that is necessary on your part is a scrupulous attention to my directions.
And here let me put in a word of caution. Where you see “_Red Lights, Green Lights, Purple Lights_” written over the formulæ above, you are to remember distinctly that I use the word “LIGHTS” to distinguish this branch of pyrotechny, and these compositions, from those which I mean to treat of under the title of coloured “FIRES.” By coloured lights I mean small cases, of the 1 or 2-oz. size, filled with either of the above compositions from No. 19 to No. 26 inclusive. _These compositions are not adapted for the purpose of producing coloured FIRES, such as are employed to light up gardens, avenues, buildings, &c._ They are to be confined to their own use, which is _the decoration of wheels, or of any large and complicated exhibition fireworks_. For this purpose they _will_ answer _well_, and for the other _they will not answer at all_. And having now explained the distinction between coloured LIGHTS and FIRES, I must ask my readers not to lay the blame upon me if, when employing my compositions for purposes for which they were never intended, they find they do not succeed.
[Illustration:
Fig. 74. ]
But we have still to speak of the way in which these coloured lights are to be fastened to the pieces which they are designed to decorate. The most common way of doing this is to drive a nail into the wooden framework of the piece at the place where you wish to place the coloured light, and to tie the case which contains it to this nail. Two nails, like “two heads,” are better than one, and the case may be secured as shown in the annexed sketch (fig. 74). A represents the coloured light case; B the string which is passed round its lower clayed end, by means of which it is secured to the two nails, C C, which are driven into the wooden framework. This mode of fastening is very simple and effective for attaching the coloured fire cases to the framework of a _fixed_ piece. But in the case of a wheel, or any piece which has motion, it is, in my opinion, very desirable to give them a position like that of the _wheel-cases_—_i.e._, to let them revolve with their mouths in the opposite direction to that of the motion of the wheel. This is easily done, either by fastening them between the spokes of a large wheel, or, in the case of a small one, by driving in a longer nail than is necessary, and bending down the head of it in the desired direction, and fastening the coloured light case to this bent part (fig. 75).
[Illustration:
Fig. 75. ]
By this means you will have no difficulty in attaching these little decorations in any place, to any part of the framework of your piece, or in any direction. The object of turning the mouth away from the direction in which the piece moves is that the resistance offered by the air during its revolution may not interfere with the easy combustion of the coloured light.
But we have yet to say a few words about the filling these 1 or 2-oz. cases, and their priming.
The compositions used for this purpose do not require, it must be remembered, to be _rammed_ into the cases; they only need be _pressed in_ so firmly that their motion during combustion shall not shake them out. Of course they should be _uniformly_ pressed in, and this is simply done by pressing in only a small quantity at a time.
With regard to their priming, this may be done in either of the following ways—by smearing into their mouths some wetted meal-powder, or, what is better, by pressing into their mouths a piece of quick-match, and then pressing a little of the coloured composition over that, and allowing the end of the match to project about half-an-inch. But in whatever way they are primed they must have two rounds of some thin paper pasted round their mouths, and projecting an inch or so beyond them, into which the leaders can be tied which are to connect them with the other cases of the piece.
In the case of small wheels, in which only one of these coloured light cases is to be employed, it will be advisable to fill it with compositions of different colours. Press in first enough red-light composition to fill one-third of the case; then enough purple to occupy another third, and fill the remainder of the case with green composition. By this means you will be able to vary your effects to any extent.
I now wish to give you directions for making a very beautiful and effective firework, in which these coloured lights play a prominent part. I must refer you to the page of illustrations which accompanies this paper, in order that you may have no difficulty in understanding the directions which I am now about to offer.
In its general working the piece is very similar to that which I have described under the name of “Brilliant Wheel” at paragraph 43. But it is at the same time a great improvement upon the one there spoken of. Cut a piece of deal or beech board into the shape drawn at _A A_. (fig. 76). This should be at least half-an-inch in thickness, and not less than three feet in length. When you have shaped it as you intend to leave it, find its centre, the point at which it balances. Through this point bore a hole of such a size as will easily admit the iron spindle which screws into your firework post (fig. 70). At each end of this wooden frame place three wheel-cases, taking care that the position of the mouths of these cases is so arranged that their driving power shall all be in one direction. A quick-match leader is to be carried from the _tail of the extreme case at each end to the mouth of the next_, and then from the tail of these to the mouths of the third at each end.
Two more pieces of wood (represented at _B B_. fig. 76) will now be required, each about twelve inches long, five-eighths of an inch wide, and three-eighths of an inch thick. They must have a hole bored through them, into which a spindle or smooth round nail can pass easily. _But this hole must not be in their centre_; it should be bored about four inches from one end, which will leave eight inches on the other side of the hole. Through these holes drive a smooth round nail into the long framework of the piece, exactly half-way between its centre and the innermost wheel-cases. The object of hanging these two pieces _not_ by their centre of balance is that one end being longer, and therefore heavier, than the other, may cause the pieces to fall round by their own weight, as the firework makes its revolutions. To these two pieces coloured lights are attached at each end in such a position that they shall project horizontally at right angles with the pieces _B B_. This will be seen clearly by reference to the drawing at _C C_. (fig. 77), which is intended to give you a side view of the same piece. It must not be forgotten that the satisfactory performance of this firework depends mainly upon the exactness and true adjustment of the woodwork. Unless the revolving pieces are neatly hung, and the balance of the main framework is true, you must not expect success.
The coloured lights may be arranged as follows:—A green and a red light on one of the revolving pieces, and a purple and red on the other. These coloured lights are all to be connected together and with the mouths of the two extreme wheel-cases by quick-match. It will be obvious, then, that the coloured lights must be so prepared as to last during the combustion of the three driving cases.
The drawing at (fig. 78) represents a rather better position for the wheel-cases than that given at (fig. 76).
The diagram (fig. 79) represents a wheel frame, to which are attached at _f f f_ coloured lights. The position there indicated is a very good one for coloured lights when required for wheels of any such make as that in the drawing. You must not forget that they are all to be placed at _different distances from the centre of the wheel_. They may, of course, be made to play their part at any period of the wheel’s revolution. The coloured lights, for whose manufacture I have given directions above, are very valuable auxiliaries in nearly all exhibition pieces, and that we shall have occasion to call them in frequently to our aid as our practical pyrotechny becomes more advanced, and our enthusiasm in the art leads us to search for new combinations and effects.
TOURBILLONS—PLAIN AND BRILLIANT.
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.