Part 4
Now let me tell you that the success of rocket compositions depends upon two things—the intimate union of their ingredients, and the fineness or coarseness of the charcoal. Such charcoal as you can procure at a chemist’s ready pounded will be of no use whatever to you, for it is in far too fine a state of subdivision. You will require a much coarser charcoal for the most part, and one not of the same coarseness or fineness throughout. If you could make a mixture containing charcoal of three different degrees of fineness—the first moderately fine, the next in pieces of the size of grains of ordinary sporting gunpowder, and the third of the size of large poppy seeds—and take equal parts of each of these three you will find that you have a mixture very serviceable for rocket purposes. But you can procure of Mr. Darby, whom I have mentioned before, a mixed charcoal which will save you the trouble of sifting. I recommend you, however, to use no charcoal that will not pass readily through your 20-mesh mixer, for your object is not to have your charcoal in large pieces, but to have a certain proportion of it coarser than the rest. You will find that the larger your proportion of coarse charcoal is, the slower your composition will be, and, within certain limits, the more fine charcoal you employ, the quicker it will be. Now, as the sparks produced by coarse charcoal remain visible in the air much longer and are much larger, than those produced by fine charcoal, I think it advisable to employ a good proportion of the coarse and in order to make up the strength that the composition loses by this plan, I take a smaller proportion of sulphur, as you will see by comparing formulas Nos. 1 and 2, and at the same time add a certain quantity of meal-powder. All these ingredients may be procured of Mr. Darby. The mode of mixing them is as follows:—Weigh out your quantities of nitre, sulphur, and meal-powder, mix them well together, and pass them through your 40-mesh sifter. This you will have no difficulty in doing, because the condition in which you purchase them is one of fine powder; your meal-powder especially cannot be too finely sifted for this purpose. You will find it a great convenience to add to this mixture a few drops of methylated spirits of wine or gin—a very slight quantity will suffice to render it less dusty—but you must bear in mind that whenever either of these liquids is employed, the composition will be sure to rust the steel spindle around which it is driven, unless you take the precaution of rubbing it over with a little oil or grease after using and before putting it away. Next add your charcoal. Stir the whole together, and pass the mixture two or three times through your 20-mesh mixer; by this means it will be thoroughly incorporated and fit for use.
ROCKET RAMMING.
6. Now we come to the actual ramming of the rockets; and, unless you intend to be a great nuisance to your friends and neighbours, you had better not dream of performing this operation indoors, it being productive of much noise and jarring; and you will find that they will not take much interest in your pyrotechnic progress when they have been annoyed and deafened by your frantic efforts for their amusement. You had better choose, therefore, some place either out-of-doors, or in an outhouse, where you are not likely to be interrupted or interfered with; the outhouse, of course, will be preferable, because there you will not be exposed to wind and weather, the former of which, especially, is often a source of considerable inconvenience when working out-of-doors. But whatever place you decide upon, you must have a very solid block of some kind, which is better made either of wood or stone, and must be set upon, or let into, solid ground. I should think that you will find no difficulty in meeting with one, made of either of these materials, in any carpenter’s or builder’s yard; odd pieces of stone and timber which would answer your purpose may generally be procured for a few pence. The stone block which I use is about 12 + 8 + 8 inches. On your block I recommend you to put nothing but the wooden block into which your spindle is fixed. The composition which you are using should never be placed upon it, because it is sure to become to some extent unmixed by the concussion caused by the blows of your mallet, for the particles of any coarse ingredient which it contains will find their way to the surface. You will find it advisable to have your block, and the table on which your tools and composition are placed, of such a height from the ground that, in working, you need not stoop or put yourself into any uncomfortable attitude.
Next we have to consider what is the most convenient receptacle for your composition while your cases are being filled with it. I use a copper scoop capable of holding about 8 ounces of composition, made something like an open coal-scuttle in form, which I have always found very convenient, and which is represented in the annexed woodcut (fig. 17).
You will next require a small ladle made of thin copper or brass, of such a size that it will take up just as much composition as you should put into your case at a time, and will admit of being passed into the case. By means of this you will be able to drive in the composition very uniformly, for by giving a certain number of blows of a certain power to each ladleful, you can be sure of an equal compression throughout the length of the case. Such a ladle Mr. Newman will supply with your rocket tools, of the right size for filling ¼ lb. cases.
I will now suppose you to be ready at the ramming-block, with all your tools about you, your composition ready, and your case driven firmly down over your spindle. I strongly recommend a slight moistening of the composition as directed above before you begin to ram it. Now, taking the longest of the drifts (fig. 13) in your left hand, insert into the case when the first ladleful of composition has been put in. You are not to suppose that by “a ladleful” I mean as much composition as can be heaped up upon the ladle or scoop, but as much as will lie within it after you have passed the drift over its surface, and have levelled the composition to the height of its sides. To this first ladleful of composition give _fourteen_ blows with the mallet: it is not necessary to exert much force in this operation, for the weight of the mallet will be nearly enough to do the work for you; and you will find that after each stroke the mallet will recoil with the blow to a point almost high enough to be the starting-point for the next stroke. Having given the proper number of blows, take another ladleful of composition, and when you have put it into the case, drive it down in the same manner as the former one with the same number of blows. Then for your third ladleful take the longest drift but one, which must be used for this and the following ladleful, giving to each of them _sixteen_ blows. Then take the shortest hollow drift, and use this for as many ladlefuls as will make the composition rise to the top of the steel spindle, giving eighteen blows to each of them. Then by inserting the short, solid drift, you will be able to measure the distance between the top of the spindle and the top of the case. When you have taken this measurement, make a mark, on _the outside_ of the case, which will show you how high the spindle rises on the inside. By adopting this plan, or any other that may occur to you as simple, you will always be able to ram the same quantity of solid composition above the spindle. This is really an important matter, and one on which depends mainly the beauty of your rocket’s performance when it reaches its greatest elevation in the air. There are great varieties of opinion as to what should be the quantity of composition rammed solid above the spindle, and it is a much more common matter to find too little than too much composition used for this purpose. The effect of using too little is, that the rocket does not fairly arrive at its turn before its stars or other decorations are thrown out. This, in my opinion, is a considerable fault; for it robs the rocket of a great deal of the elegance of its flight, and gives one the idea that it is in a hurry to get its work over. Nothing but actual experience and observation will enable any one to decide which he considers the proper quantity of solid composition. I consider the best length for this part of the rocket to be that of _the exterior diameter of the case_—that is, an inch or rather more for rockets of the ¼lb. size. Larger rockets, I have always found, do not require quite so much in proportion; smaller rockets rather more. You should give twenty blows with the mallet to each ladleful of this solid composition. I am well aware that this number of blows sounds like a great deal of hard work, but you may rest assured that these twenty blows, given as I have directed above, will occupy only five or six seconds of time, at the cost of very little exertion.
Having now completed the ramming of the composition into your case, you will next require some common potter’s clay in dry powder; this can be procured of Mr. Darby in a condition proper for use. Take half-a-ladleful of it, and ram it down very hard upon the top of the composition with the solid drift. This clay when thus compressed will form an end to your rocket nearly as hard as stone—not so hard, however, but that you can bore a hole through it about ⁵⁄₁₆ths of an inch in diameter, which will allow of the necessary connexion between the rammed composition and the stars or other contents of the head of your rocket. In the next place I will speak of the
PRIMING.
7. This may be done in two ways; for exhibition purposes I should merely put into the mouth of the rocket some meal-powder-paste made as follows:—Make a rather soft, but not too liquid paste, by moistening meal-powder with gum-water made of the strength of 2-oz. of gum-arabic to a pint of water. With the flattened end of a stick rub some of this paste into the cup formed at the choked end of the rocket, taking care that none of it _is left in the choke_ or narrow aperture at which the fire from the rocket has to find vent; for, if any should remain there, the rocket when fired is almost certain to burst. Any of the paste that happens to be forced into this aperture may easily be taken out afterwards by means of a piece of wire or stout pin.
Your rocket is now finished as far as its ascending power is concerned.
ROCKET POT.
8. I will tell you my method of making the head, or _pot_ as it is termed, of the rocket. You must have a piece of hard wood turned of a shape like that indicated in the following woodcut (fig. 18). The straight part of this should be about 4 inches long, and a shade larger in diameter than the exterior of your rocket-case—that is, about 1⅛ inch in diameter, if you adopt the method of cutting up your imperial board and 70-lb. brown paper given in _this_ chapter. Now take some moderately thick brown paper, and cut it into strips about 5 inches in width and 8 in length; each of these strips will be long enough to go twice round the _pot-former_ described above. When you have pasted as much of each strip as will not lie actually against the former, roll it up straightly and pinch in one end; you will thus have made a cylinder of paper (fig. 19) closed at one end, the other end of which will fit nicely over the clay end of your rocket. This is the pot of the rocket, which is to contain your stars, rains, &c.
ROCKET CONES.
9. You will next require a turned wooden former on which you can make paper cones of such a size at their base that they can be neatly pasted on to the top of your pots—that is, the base of these cones should have the same diameter as the pots. Although such conical caps are by no means necessary, yet they are a very great assistance to the rocket in its ascent, enabling it to rise with much less resistance through the air. The cone-former is represented in the annexed woodcut (fig. 20). To make these cones upon it, cut out as many circular pieces of brown paper as you require, the semi-diameter of which must be slightly greater than the height of the cones that you have to make. Then cut or tear these circles into halves and paste them on one side. Now place the first half-circle upon the former, pasted side outwards, taking care that the apex of the cone beat the point marked A in fig. 21. Then fold the brown paper neatly round the cone-former, and when you have made it to sit as closely to it as possible, proceed in the same manner with the other half-circle, putting it upon the first, pasted side inwards. The paper cones thus made must next be covered with one thickness of thin paper cut large enough to extend ½ an inch or rather more beyond the open end of the cone, and this projecting part, when notched all round with your scissors, can be pasted down round the top of the rocket pot. When this is done the pot will present the appearance of annexed illustration (fig. 22).
ROCKET STARS.
10. When all the pasting that has been necessary in making the pots is thoroughly dry, the filling them with stars is all that remains to be done for the completion of the rocket. You will find that the ¼lb. rocket will carry an ounce of stars well. After weighing out your stars, then, into parcels of this weight, empty one of these parcels into each pot. You will next require some sort of powder to strew among the stars which shall have the effect of igniting them and at the same time of bursting the pot. I have always found meal-powder by itself to be too rapid in its explosion to convey the fire to all the stars; many of them are blown out of the pot, never taking fire at all. The mixture which I should recommend you to use is the following:—
Meal-powder 6 parts. Fine charcoal 1 part.
Charcoal added to the meal-powder in the above proportion will render its combustion slow enough to light all the stars, without being too slow to burst the pot. Of this mixture take a ladleful (I mean the ladle which you use in filling your cases), and put it with the stars into the pot, which must now be securely glued over the clay end of the rocket-case.
ROCKET-STICK.
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.
GOLDEN RAIN.
13. There is another and exceedingly beautiful decoration for rocket heads which is called golden rain. This is by no means a difficult thing to make. Some small paper cases are made, about 2 inches long and of the size of goosequills; these are filled with a sparkling composition and primed with wetted gunpowder. They are placed, mouth downwards, in the head of the rocket, and arranged in such a manner that they may _all_ be ignited. At the bursting of the rocket, they will describe a series of beautiful ringlets of sparkling fire.
I have now enumerated as many different kinds of stars, &c., as will provide you with the means of producing any amount of variety. I now come to the details of the manufacture of these decorations. We will begin with the ordinary
BRILLIANT STARS.
14. First, let me impress upon you the necessity of seeing that _all ingredients used in star compositions are in as fine a powder as possible_. You cannot have them too fine or too well incorporated and mixed. The following is the formula which I employ for the
COMMON BRILLIANT STARS. Nitre 16 parts Sulphur 8 „ Sulphuret of antimony 4 „ Meal-powder 3 „
Let all these ingredients be in fine powder, and, having carefully weighed out the quantities, mix them thoroughly. Next, take some gum-water of the strength previously mentioned—viz., two ounces of gum-arabic dissolved in a pint of warm water. Spread your star composition upon a piece of zinc plate or slate, and add to it a little of the gum-water at a time, taking care to stir the composition about _well_ till all the moisture is equally diffused through the whole. It is not necessary that this composition should be made _wet_, but only something like brown sugar in moistness, so that it will _bind well_ when pressed together. When you think this is sufficiently done, roll or press the composition into a flat shape like a thick pancake, and make it as square, or, at all events, as rectangular, as possible. Its thickness should be about _a quarter of an inch_. You will find a large spatula a very convenient tool in this operation, both for flattening the cake of composition and for getting it into a convenient shape. Now take your spatula, and with it score the composition across both ways, so that you have it divided into a number of little cubes, fig. 30.
It may then be set aside to dry in a warm place; it will be forty-eight hours before it is fit for use in summer, and about a week in winter. When dry you will have no trouble in separating the cubes at the marks left by the spatula.