Part 11
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.
COLOURED FIRES.
52. _Coloured fires_, such as are employed for illuminating gardens, shrubberies, avenues, buildings, &c., will now occupy our attention.
[Illustration:
Fig. 90.—Former for Coloured Fire Cases.
Fig. 91.—Iron Fork to support Coloured Fires while burning. ]
This species of firework is of very simple construction, and requires only an ordinary amount of care in order to insure its success. And it is very fortunate that so necessary an item in the programme of a pyrotechnic display is one which can be relied upon for producing so beautiful and surprising an effect. I have known spectators more pleased with the coloured fires in an exhibition than with any other of its features; and I am convinced, that by a well-contrived introduction and arrangement of them, results may be produced at least as effective and satisfactory as by any combination of a much more elaborate character.
But before entering upon the description of their manufacture, it will be necessary for me to remind you of some information that I have already given in the portion devoted to coloured stars, in order that you may be induced not to prepare your colours for an exhibition until you know _what you are going to prepare them for_—that is, what sort of a place they are required to light up.
What I have before said under the head of Coloured _Stars_ with regard to the illuminating or reflective properties of this or that composition, must more than ever be borne in mind in the matter of coloured _fires_. There are two kinds of fires used in pyrotechny—one burning with a considerable depth and richness of tint, but possessing a very moderate illuminating power, the other having great brilliancy and reflective power, but not the same depth of colour. Now with this plain distinction before us, there will be no difficulty in selecting such composition as will produce the desired effect. You have simply to make up your mind beforehand whether you require a colour of considerable intensity, _which you may gaze at while it burns_, or one whose beauty will be seen to advantage, _not in itself_, but in its reflection upon those objects which are within reach of its illumination.
The formulas which I shall give will be characterised as “reflective,” or “intense in colour,” and if they are only made up with pure, dry, and fine ingredients, will, I am sure, give as good results as need be desired.
In the first place the preparation of the cases is to be considered. With regard to these it must be remembered that they are required _to burn with the composition_, and must not be made too thick or hard on that account. The thicker they are, the more will their consumption interfere with the burning of, and impair the colour produced by, the composition. A sheet of 60lb. or 70-lb. brown paper cut up into nine strips in the manner represented at fig. 89 will furnish you some very good cases for the purpose. Each of these strips will be a little over three inches in width, which, in my opinion, is quite sufficient. The former for these cases is made of wood, and should be from an inch and a-half to an inch and three-quarters in diameter, and about four inches long, irrespectively of its handle. The drift for filling the cases may be of the same length, and _one-sixteenth of an inch smaller in diameter_, so as to admit of its passing easily in and out of the case.
[Illustration:
Fig. 89. ]
The difficulty that I have always experienced with regard to these cases has been this—they must be made of a certain thickness, in order that they may not be broken during the process of ramming in the composition. This process is, I believe, indispensable. At all events, I find it so, for _if the composition be only pressed in loosely, and not rammed, it will fall to the ground in burning lumps_, instead of burning slowly and evenly in and with its case; and if the cases be made unnecessarily thick, either the composition will not burn freely enough, or its colour will be impaired (and this will be particularly the case with regard to _green_ fires), or, what is more probable still, both these calamities will happen at once, and render your production doubly ineffective.
Now my plan for obviating the difficulty has been to increase the _diameter_ of the cases, and thereby to gain a greater body of composition in proportion to their _thickness_. This plan I have found to answer very well, and so I can conscientiously recommend it to you.
Take, then, one of the strips of paper, cut as recommended above, and, pasting it all over on one side, roll it evenly round your former, having previously brushed a little paste over the former to prevent the paper sticking to it. Having rolled the strip up evenly and smoothly, take it off from the former, and set it by to dry. It will readily be perceived that these cases are among the easiest to make.
And now we may pass on to the important subject of the compositions with which these cases are to be filled.
The first of these is known as the:—
COMMON BENGAL LIGHT.
53. It has a bluish-white colour, and is called by some pyrotechnists “Artificial Moonlight.” Its composition is:—
No. 1. Nitre 12 parts. Sulphur 4 „ Antimony 1 part.
Orpiment or realgar may be substituted for the antimony, in which case there will be less smoke.
The above is the commonest sort of Bengal light. It gives a pretty effect, but has no great illuminating power.
54. WHITE FIRE.
WHITE FIRE. No. 2. Nitre 32 parts. Sulphur 8 „ Regulus of antimony 12 „ Red lead 11 „
This is a French composition, introduced by Chertier, and is remarkable for its whiteness. It will be found a very useful composition, possessing a fair reflective power.
WHITE FIRE. No. 3. Nitre 24 parts. Sulphur 7 „ Realgar 2 to 3 „ Antimony 1 part.
This I always find the most serviceable composition on the whole. It does not possess the intense whiteness of No. 2, but has a slight tint of blue; and this difference alone would gain it the preference in my judgment. But it has also a greater illuminating power, and is decidedly the best composition that I have yet been able to find.
The red lead recommended in composition No. 2 can be purchased in fine powder, ready for use, at any painter’s or chemist’s shop.
YELLOW FIRE.
55. We may now proceed to the formula for—
YELLOW FIRE. No. 4. Nitrate of baryta 36 parts. Oxalate of soda 6 „ Sulphur 3 „ Shellac 5 „
This composition produces a good colour and has a moderate reflective power. Its principal merit lies in the fact that it will keep good for any length of time after it is mixed, and can be made with samples of nitrate of baryta which will not produce a good green.
YELLOW FIRE. No. 5. Nitrate of soda 48 parts. Sulphur 16 „ Antimony 4 „ Charcoal (fine) 1 part.
This is decidedly the best formula for yellow fires, as far as effect is concerned. But the nitrate of soda is so highly deliquescent that the composition must on no account be made up longer before use than is absolutely necessary. Yellow fires are not much used in pyrotechnic exhibitions. I suppose this is to be accounted for by the extraordinary power that they possess of giving to all objects, especially the human face, a ghastly and death-like appearance, anything but agreeable to behold. I have no doubt, however, that some of my younger readers, knowing this, will set a higher value upon the formulas for yellow fire, for the fun of showing off the spectators of their exhibitions to the greatest possible disadvantage. Especial notice should be taken of the complete annihilation of colour in flowers, dresses, &c., by this yellow light. The effect is, of course, very similar to that produced by the burning of spirits of wine or naptha holding salt in solution. This latter is known as the _monochromatic light_; that is, a light in which only one of the colours of the spectrum is shown.
Although I do not remember ever having seen a yellow fire used in any large exhibition of fireworks, I have given the above formulas in order to render my paper upon the subject as complete as possible.
The next colour with which we shall deal will be the
GREEN FIRE.
56. For this colour I shall give three formulas, all of which I have found good, notwithstanding the universally acknowledged difficulty of obtaining a real green colour. This difficulty has arisen, I believe, solely from the imperfections and impurities in the nitrate of baryta which finds its way into the market. This salt should be prepared from the sulphate of baryta, _and not from the carbonate_; and I think I am right in stating that it is far more generally prepared from the carbonate than from the sulphate. When this is the case you either get a very decent _yellow_ colour from the sample, or you get a salt which burns about as green as a very bad specimen of nitre will burn. My readers will readily understand that nitre ought not to be so green as to admit of this.
And now, before giving the formulas, it only remains for me to say that if you have but a really good sample of _dry_ nitrate of baryta _in fine powder_, you ought to be able to make from the following receipts a green fire which will answer any purpose:—
GREEN FIRE. No. 6. Nitrate of baryta 45 parts. Chlorate of potash 10 „ Sulphur 10 „ Antimony (sulphide) 1 part.
The above formula gives a pure but pale green. It has a most intense illuminating power, and for this cause is very valuable. The addition of a little nitrate of baryta will render the composition more intense in colour, but will detract from its rapidity of combustion, and therefore from its illuminative power.
No. 7. Nitrate of baryta 77 parts. Chlorate of potash 5 „ Sulphur 12 „ Charcoal 2 „ Orpiment or realgar 2 „ Shellac 2 „
Composition No. 7 is a very old one, slightly altered to make it burn more freely. It gives a more intensely green colour than No. 6, but has not the same advantage with regard to its illuminative properties. It is, however, a very serviceable and inexpensive receipt to employ.
We now come to the best of all the formulas for green fire that I have been able to meet with, and one which has thoroughly satisfied me. It is almost the same as that recommended by Chertier, the difference consisting in a slight decrease in the quantity of calomel, which enables the composition to burn rather more freely and adds to its reflective power. I have seen a real emerald green produced by this composition when good nitrate of baryta has been used, but in this, as in the case of all other green fires, if you do not succeed you may generally fasten your suspicions upon the nitrate of baryta.
No. 8. Nitrate of baryta 40 parts. Chlorate of potash 4 „ Sulphur 8 „ Calomel 8 „ Charcoal (fine) 2 „ Shellac 1 part.
I do not think that any better formula than this can be needed. It carries with it a better combination of intensity of colour with intensity of illuminating power than any coloured fire composition that I am acquainted with.
PURPLE FIRE.
57. I have next a formula to offer which I think has considerable merits of its own. It produces a purple colour of a very pleasing tint, and has also very considerable illuminating power. I have never seen a colour of this kind employed in any pyrotechnic exhibition, but I believe it to be an effective composition, and one certainly that will make a change from the ordinary routine of white, green, and red. I shall dignify it by the title of—
PURPLE FIRE. No. 9. Nitre 48 parts. Sulphide of copper 12 „ Sulphur 12 „ Calomel 6 „ Arsenic 6 „ Nitrate of strontia 6 „ Chlorate of potash 4 „ Shellac 4 „ Charcoal (fine) 1 part.