Rockets are charged in choked cases, on a spindle, to leave a hollow up the middle, through which the fire may be communicated to nearly the whole of the composition at once: this causes the sudden generation of an enormous quantity of elastic vapour, which, being unable to escape instantly through the contracted aperture left for its exit, exerts its pressure in the contrary direction, and hurries the rocket forward. A stick, attached to it, guides it, like the rudder of a vessel, or tail of a bird, or fish; while its weight and leverage keep the centre of gravity a little below the case, and prevent the rocket from pitching over. Its manufacture, therefore, from the commencement of cutting the paper for the case, to its finish of fitting on the stick, requires an accurate adjustment of all its parts. Disregarding the trade names of pound, ounce,&c., which, now that moulds are dispensed with, are useful only for enabling the makers, from tradition, to understand each other; the internal diameter, instead of the external, as formerly, may be selected, from which to compute the relative measures. Taking the bore of the case as unity, the proportions will be as follow:—
These proportions are most readily calculated by taking the diameter in eighths of an inch. Selecting, for instance, a6⁄8rocket, we have,6⁄8, inner diameter; half as much again,9⁄8, outer diameter.
Taking the numerator as inches: 6 inches, length of case;3⁄4of this, or, which is the same,1⁄2the outer diameter, as inches, 41⁄2inches, length of spindle; putting 20 for the denominator, instead of 8 (8 being2⁄5of 20),6⁄20of an inch, bottom diameter of spindle; 6 × 8, (numerator multiplied by denominator) = 48 inches, length of stick;3⁄8by3⁄8, size of stick.
The following table exhibits the usual sizes in inches.
Have the former, fig. 7, a brass tube6⁄8of an inch external diameter; the gauge, fig. 8, with a9⁄8aperture; procure some imperial brown paper, 70 lb. or 84 lb., the thicker and heavier the better. The best kind is madeof old ropes, is air-dried, and rough. This is not easily obtained now. The smooth machine-made, cylinder-dried answers very well. The sort used for laying under carpets, and which is 5 feet broad, is almost equal to the original rough imperial, and should be procured, if possible, in preference to the smooth. Cut it into strips 6 inches wide. Paste the pieces well, and roll the cases as hard as possible, with the rolling board fig. 6, till they fit the gauge. Lay them by for a few hours to get partially dry. They must, then, be choked or strangled, about half a diameter from one end of the case, that end that lay nearest to the left hand in rolling, till they assume the shape of the neck of a vial. For this purpose have a cylindrical piece of deal, alder, or any kind of wood, fig. 24, about 9 or 10 inches long, made to fit easily into the case; cut it into 2 pieces, a and b; b may be an inch and a half long; round off the ends, just cut. In a, fasten a screw, the solid wire, or uncut part of which, is1⁄4of an inch thick; saw, or file off the head, and slightly taper the part projecting; in the piece b bore a hole to just fit the wire of a. Slip b upona, and push them into the case, so that the interval between the two reaches within about1⁄2an inch of one end of the case; slightly draw out b, to leave a neck, or hollow, round which to form the choke; fix a staple, or screw-eye in a post: tie to it one end of a piece of cord, about a yard long, and1⁄10of an inch thick; fasten the other end round the middle of a stick, for a handle; take hold of the stick with the right hand; hold the case in the left; pass the cord round the space left vacant and gradually tighten it, turning the case round and round, so as to pinch it in equally on all sides, till it assumes the shape of fig. 23. Hitch a piece of string, about1⁄16of an inch thick, a few times round the neck, until it is filled up flush with the other part of the case, remove the choker, and hang the case up to dry. A hitch is made by simply bending the string backwards into a loop, like fig. 22; passing it round the choke; pulling it tight; looping it again, again passing it round the choke, and so on. The first loop is called a half hitch, and will not hold of itself; the second loop completes the hitch, and makes it hold: the remaining hitches are for filling up the choke, and restoring the cylindrical shape. Practise, by hitching the string upon your thumb, 4 or 5 times: it will hold after the second loop; but push it off at the end, and it will all fall loose again.
A case must not be choked when wet, or it will tear; nor must it be too dry, or it will be difficult to choke it at all. The drier, however, it can be choked, the better. Experience is the only guide. If properly dry, the wrinkles of the choke will be small, and perfectly regular. Should the string stick to the case, chalk it; but this is not likely to occur unless the paper is too wet. Have a foot, fig. 16, turned of ash, or beech, or box, with a hemispherical nipple,6⁄8of an inch diameter, as drawn. Bore it with a twist drill, or nosebit, to the depth of an inch and a half. Procure a brass, iron, or steel wire, but preferably brass, 6 inches long, and3⁄10of an inch diameter, and perfectly straight. Cut, on one end of it, a screw, 11⁄2inch long, fix it in a vice, wet the screw with glue, and screw the foot on. File the 41⁄2inches gradually tapering. Theobject of tapering it is simply to make it deliver. A cylindrical hollow up the rocket would answer as well, but the spindle could not be got out. The more conically true it is tapered, of course, the better. Finish it off with a very fine file, and smooth it with glass paper. The block into which it is screwed may be larger than drawn; the bottom should be turned slightly concave, to make it stand firm, on the same principle as the bottoms of plates, cups, &c., are made with a rim. The block and spindle are better if cast in gun-metal, in one solid piece: the pattern to give to the caster should be in one solid piece of wood. After casting, the rough parts must be filed smooth; not many turners will be found willing to undertake to turn it.
The next articles required are a setting-down piece, fig. 17; three hollow rammers, or drifts, figs. 18, 19, and 20; and one solid rammer, fig. 21. They are simply cylindrical pieces of wood, turned with a head, to bear the blows of the mallet. Beech, or box free from knots, will answer. The lengths of figs. 18, 19, 20, and 21, are to be 8, 6, 4, and 2 diameters, respectively, exclusive of the head;that is, 6, 41⁄2, 3, and 11⁄2inches. The hollow drifts are to have a cylindrical, not conical, hole, bored up them, with a nosebit, or twist drill, to within one inch of the handle, so as to clear the spindle by1⁄2an inch, to allow of any dust being driven up it. The hollow in figs. 17 and 18 must be large enough to fit the spindle loosely at a; in fig. 19, a trifle smaller, to fit loosely at b; and in fig. 20, a trifle smaller still, to fit loosely at c.
The next requisite is a mallet, fig. 25, which may be of ash, or beech. It may be a cylinder, 5 inches long, and 3 inches diameter, with a handle about 5 inches long, and 1 inch diameter. Let it be turned at the end slightly concave, like the bottom of fig. 16, that it may be set to stand upright, like a wine bottle. Or the head may be made 3 inches square, like fig. 26; or, a small carpenter's mallet, about a pound and a quarter weight, will answer.
The first requisite is a solid block of wood, 6 or 8 inches square, and 18 or 20 high. This is indispensable. A piece of an oldoak gate post, answers well. It must be set upon the ground, or on a flag stone, not on a floor. It is impossible to ram a rocket properly on the floor, because of the vibration. It is, also, necessary to sit, not stand, at the work.
Put the setting down piece, fig. 17, into the case; press the case over the spindle, and give the head a few blows with the mallet; this will smooth out the wrinkles of the choke, which is all that fig. 17 is used for. Now put in a very little powdered clay, and mallet it with fig. 18; as much clay as will reach up1⁄12of an inch will be sufficient; its object is to preserve the choke from burning, and getting enlarged. One cannot be too precautious with rockets. Now put in a scoop of rocket fuse, insert drift, fig. 18, and mallet the fuse in firm, with about a dozen and a half blows, or till it offers a resistance to the hand. The blows must be light and numerous, not slow and heavy, like driving a post into the ground. 18 blows with a momentum of 3, will consolidate the fuse: 3 violent blows, with a momentum of 18, would perhaps bend the case, or drive the dust up into your eyes. The mallet neednot be lifted above 4 or 5 inches at a time. If the rocket is not rammed firm throughout, it will, upon lighting, explode.
As soon as the case is charged about 11⁄2inch, make a pencil or ink mark, round the drift, where it stands level with the top of the case, for future guidance; then charge another 11⁄2inch with the second rammer, fig. 19, and mark it in like manner; proceed in the same way with fig. 20. It is obvious that if fig. 19 were used too soon it would get split by the spindle being driven up it, and the spindle would be bent or broken, hence the advisability of marking the drifts to know when to lay aside one, and take the other. Just before you get to the top of the spindle, put in the solid rammer to feel how high the spindle reaches near the top of the case; hold it by the thumb and finger to keep the distance, and mark it down the outside of the case, by indenting the case with the edge of the drift. Exactly 11⁄3diameter, that is, in this case, exactly 1 inch, above this indentation make another mark: then as soon as you have covered the spindle, till you can no longer see it, with the use of fig. 20,begin charging with the solid drift, fig. 21, till the composition inside is level with the top mark. This being done drive in a little dry clay, till the case is full. Remove the rocket from the spindle, by giving it a turn or two round to the right, not backwards; then bore a hole through the clay, till you can see the composition, with a3⁄16inch shell-bit. The shell-bit should be fixed in a handle, and kept for the purpose. It is not advisable to use a stock and bit, unless the bit is shielded, as it is apt to bore too deeply. The bit may be fixed in a handle, by boring a large hole in the handle, and pouring in melted lead, or pressing in plaster of paris.
Instead of driving in dry clay on the top of the composition, a little plaster of paris may be pressed in; this, when dry, will allow of a perfectly clean hole being bored through it; whereas the clay is apt to crumble, and chip out. The object of the clay, or plaster, is to prevent the composition, which, containing much charcoal, does not bind well, from getting disturbed, and the solid part diminished, which would cause the stars to be ignited while the rocket was ascending, orthe fuse, perhaps, to blow through at the beginning. A piece or two of naked quickmatch is to be inserted in the hole through the clay or plaster, and a long piece is to be pushed up the core, or hollow, of the rocket, as far as it will go; it is, then, to be cut off flush with the mouth, and fastened to the side with a little dab of wetted meal powder, pressed on it with the blade of a knife. If the rocket is intended to be lit with a port-fire, take a circular piece of touch-paper, about 2 inches diameter, slightly paste it all over, lay it in the left hand, press the mouth of the rocket down upon it, and smooth the edges of the touch-paper up round the case. Otherwise, smear the end of the case with the sash-tool dipped into meal paste, and when dry, paste a bit of touch-paper round it, and twist to a point, like a squib. The appearance of the rocket is shown at fig. 36; the dotted line round the mouth shows the touch-paper.
In driving with the hollow rammers, it generally happens that a little of the fuse gets driven up the hole; this, if allowed to accumulate, is very troublesome to remove; it should, therefore, be knocked out everytime, by holding the drift in the left hand, and giving the head a rap or two with the mallet.
The whole of the composition ought to be put in in about 12 scoops: try 2 or 3 scoops till you get one of the right size, then write upon the handle what-sized rocket it belongs to. These directions may appear minute, but they will save much trouble if attended to.
As it is convenient to know, beforehand, about what quantity of composition will be required for any particular rocket, the following formula will be useful:—
E3/ 9 = drams.
Where E denotes the size of the rocket, in eighths of an inch.
Required the quantity of fuse for a6⁄8rocket.
(6 × 6 × 6) / 9 = 4 × 6 = 24 drams = 11⁄2ounce.
For a3⁄8rocket?
(3 × 3 × 3)/9 = 3 drams.
The same weights denote the quantity of stars which the rocket will safely carry: thusan ounce and a half of stars may be put into the head of a6⁄8rocket; and 3 drams into a3⁄8rocket. Along with the stars is to be put in1⁄9the weight of the stars of bursting powder; this may be pure meal powder; or a mixture of 8 meal powder, 1 fine charcoal, well sifted together: or half meal, half grain; thus the quantity of bursting powder for a6⁄8rocket will be24⁄9= 22⁄3drams; and for a3⁄8rocket,3⁄9=1⁄3of a dram. It is advisable to keep nearly to these directions, for the weight of the stars; but it is not necessary to be minutely exact; but to ascertain whether the head is too heavy or not, take a table knife, or any thing an inch broad, and lay the rocket flat and horizontally upon it in such a manner that the commencement of the head lies close to the back edge of the knife, the cutting edge lying towards the choke: if the head pitches over, it is too heavy, and some of the stars must be taken out; if it balances, it is correct.
Rockets should be fired from two staples, or two screweyes, fixed in a post, one near the top, the other half a yard below, as in fig. 70. They should never be propped againsta wall, a chairback, a gate, or railing, as they might fall, especially on a windy night, after the touch-paper was lit, and before the fuse had caught. Every possible care should be taken in guiding them, as it is too late to think about any mischief they may cause, after they have once started.
In making rockets, it is essential, above all things, to have good nitre and charcoal. The best way, with fresh materials, is to weigh out as much nitre, charcoal, and sulphur, as will make one small rocket. Have the nitre as fine as possible, and dry it over the fire in a 6-inch frying pan, which should be kept for the purpose. If the rocket ascends well you will know that the articles are pure, and you can proceed to use them; but if the rocket does not rise, you may conclude the articles are adulterated, the nitre with salt, or that the charcoal is perhaps merely deal sawdust, burnt in a retort. In this case you must buy the nitre in crystals, and the charcoal in sticks. To powder the nitre, put it into a pipkin, pour on it a little water, set it on the fire, make the water boil, and keep stirring the nitre with a piece of wood, until it is dry andof a fine powder. Charcoal is best ground up in a coffee-mill. It must first be broken into small pieces, about the size of coffee-beans. After being ground it should be sifted through the sieve, the interstices of which are about1⁄40of an inch square. To get a correct idea of this size, lay down a line on paper, an inch long: mark it off into eight equal parts by taking the divisions from a foot-rule; then carefully divide one of the eighths into five equal parts. But the best way is to make a square deal sieve, about 8 inches square, and 3 inches deep; then nail on the bottom a piece of perforated zinc, with quarter-inch flemish tacks. The perforations are circular, and should be 20 to the inch, measured diagonally; that is, a diamond-shaped inch, or inch rhombus, consisting of 20 oblique rows, each row containing 20 holes; 20 times 20 = 400. These holes will be about the same size as the ones mentioned in the sieve, because the solid parts between the perforations are also about1⁄40of an inch. A strip of deal,1⁄4of an inch thick, should be nailed round the bottom, to keep the zinc tight. A square box for a receiver, andanother for a lid, should also be constructed, otherwise you will be smothered in sifting charcoal. Making use of the perforated zinc sieve just described, all the charcoal that goes through, fine and coarse, should be used for rockets. It need not be shaken much, but brushed through with a sash-tool. Construct a second sieve with 15 perforations to the lineal inch. Iron borings for gerbes should be sifted through this; use all that goes through. Construct, also, a third sieve with 9 perforations to the lineal inch. Nothing can equal iron and steel for making sparks; but neither will keep long from rusting, after coming in contact with nitre. Coke grains, about the size of pinheads, are a fair substitute. Beat coke into lumps about as large as peas, then grind it in a coffee-mill, and brush it through the 9-perforation sieve; sift the fine dust from what passes through: throw the dust away, and keep the grains. Porcelain may be powdered in an iron mortar, for gerbes; brush through the 9-perforation sieve; sift out the dust with a fine sieve; throw it away and keep the grains. The intense heat of the focus of the choke rendersthem incandescent; and, from their weight, they are projected to a considerable distance. They are inferior, however, to coke grains, as the latter are to steel filings. We may say, alliteratively; positive, porcelain; comparative, coke; superlative, steel.
Zinc may be obtained with half-inch perforations; a size useful for garden sieves, bottoms of soap boxes, &c.
Before grinding a fresh substance in a coffee-mill, it must be taken to pieces, brushed clean, and screwed up again. Fine lawn or hair sieves should be used for sifting chemicals; excellent sieves may be made with book-muslin: the cylinders may be 4 inches diameter, 3 deep; the muslin should be cut into a circular form, and hemmed round a piece of string; it may then be slipped over the drum or cylinder, and secured; or it may be pasted up and round the sides, and if above 4 inches diameter, two pieces of string may be crossed over the middle to strengthen it.
Charcoal may be made by putting some dry pieces of willow, alder, poplar, sycamore, maple, or almost any kind of wood, exceptthe pine or turpentine tribe, into an old iron saucepan, covering them with perfectly dry sand, and setting the saucepan in the middle of a fire, to remain red hot till the wood is completely burnt through. Remove when judged sufficiently charred; and when cold, not before, pour away the sand.
Sulphur is used in the state of sublimed sulphur, sulphur sublimatum, or flowers of sulphur, and, when mixed with nitre, requires no preparation; but as it is always more or less impregnated with sulphuric acid, as is readily shown by testing it with litmus paper, it might, on coming into contact with chlorate of potash, cause spontaneous combustion. To prevent this, it is necessary to wash the sulphur. For this purpose put it into a pan, and pour upon it boiling water, in which some salts of tartar (carbonate of potash) have been dissolved; stir it well and break down all lumps. Let it stand to subside; pour off the supernatant liquor; fill up with cold water and let it stand, to again subside. Make a conical bag, fig. 33, with a piece of linen or calico, sewed at the top, round a ring or hoop of wire, or cane, or whalebone; fasten a string toit, by which to hang it up. Put the washed sulphur into it, and hang it under a water-tap; turn the water gently on, and let it drip all night; this will wash away every trace both of acid and alkali. Afterwards hang the bag up three or four days till the sulphur is dry; it may then be bottled, and kept exclusively for colours.
Oxalate of soda may be made thus—procure 3 lbs. of carbonate of soda, the common washing soda used by the laundress, not bicarbonate of soda; boil it up in a saucepan with just as little water as will suffice to dissolve it. Dissolve, in another vessel, 1 lb. of oxalic acid in boiling water, and pour it into a deep jar, capable of holding two or three quarts; a wash-hand jug will answer. Now put to this the dissolved carbonate of soda, with a table-spoon, a spoonful at a time. A violent effervescence takes place. The soda is to be slowly added till effervescence ceases. It should be tested with a strip of litmus paper, to see if the acid is perfectly neutralized.
To prepare litmus paper, dissolve1⁄4of an ounce of litmus in an ounce and a half ofwater; when thoroughly dissolved, and the water is of a dark blue colour, take some white blotting paper, and with a sash-tool or camel's-hair pencil, go over it on both sides with the litmus solution. When dry, wet some of these prepared pieces, with the brush dipped into vinegar: this will turn them red. Dry, and preserve both. They may be cut into strips, half an inch broad; the blue strips will be tests for acids; the red, for alkalies. Wet a strip of the blue, and touch it with oxalic acid, it will turn red; wet a strip of the red, or the piece just reddened, with carbonate of soda, it will turn blue.
To make sulphuret of copper, procure some thin sheet copper, about as thick as a card; cut it into pieces, and put it into a crucible, with sulphur, a layer of sulphur, and a layer of copper alternately, till full. Set the crucible in a clear fire, and keep it red hot for an hour. Remove it; when cold, break it up, and grind it in a coffee-mill. Sift it in a lawn or book-muslin sieve as fine as possible. Half-a-pound of copper and a quarter of a pound of sulphur may be employed.
There is a black sulphide or sulphuret ofcopper produced by passing sulphuretted hydrogen through a solution of protoxide of copper: this is useless.
For want of a coffee-mill, charcoal may be beaten in a leather bag, with a hammer.
A variety of rocket fuses will be found in the Tables; the first is as good as any, and will answer for all sizes from3⁄8to12⁄8. As a rule, the fiercer fuses, containing meal powder, may be used for small rockets; but are, by no means, necessary.
A rocket, when starting, makes a roar; but this is not on account of the fierceness of the fuse, but of the extent of the surface ignited. Rocket composition, laid in a train, burns very slowly.
Rocket stars are made in three or four ways. First cut, or chopped, or naked stars. This mode is used for nitre stars only: chlorate of potash stars require different methods. It is a singular circumstance that, though chlorate of potash stars are much fiercer than nitrate of potash stars, yet the latter light without any trouble, while the former, if made in the same way, would be almost sure to miss.
Wet the composition with thin starch, or dextrine solution, or gum water, sufficiently to bind; press it into a flat mass, on a slate, or Dutch tile, with a knife, or small trowel, till about3⁄8of an inch thick. Indent the surface with the edge of the knife, in parallel lines, about3⁄8of an inch apart, and cross these with equidistant indentations, at right angles. Set the mass by, to dry gradually. When nearly dry, break it up into little3⁄8cubes, and lay them out, to dry thoroughly. The broken edges will be rough, and will catch easily.
Take a sheet of note paper, and cut it into four equal parts; each part will be about 41⁄2inches by 31⁄2. Paste and roll them on a 31⁄2/8 brass tube, so as to have the cases 41⁄2inches long. To make these into pill-boxes, perfectly true, like those used by the druggist, they must be cut in the lathe. For this purpose, turn a cylindrical piece of wood, fig. 27, which is to fit easily into the case, except at a, where it is to be turned sloping a little larger,so that when the case is slipped over it, it will bite at the part a; otherwise, on putting the chisel to it, it would slip round, without getting cut. Mark the case, with a black-lead pencil, at every half-inch; suspend it in the lathe; and cut it at the marks. Next procure a7⁄16inch punch, with which to cut out the bottoms. These are to be made of card, or bristol-board. Lay the card on a piece of sheet-lead, or the grain end of a piece of beech, and give it a smart blow or two with a hammer; keep on punching till the punch contains a dozen or more discs, then push them out. When a number are ready, press them into the pill-boxes, with a rammer that fits loosely.
The composition is to be put into these dry, and driven in with a solid rammer, and the little mallet, before described.
This was the original way of making them, but is perfectly unnecessary. Roll the tubes as directed, of two thicknesses of paper, with a little bit to lap over. Cut them across, with one sharp clip, with a strong pair of scissors. This will slightly flatten them; but they may readily be restored to the cylindrical form, by slipping them on a piece of wood, and rounding them to shape with the fingers. No bottoms need be provided, no punch used.
Rest the box on a flat surface, put in some composition, and drive it in with a brass or boxwood drift and the little mallet, till half full, as in fig. 28. Then fill up the box with more colour, set a little bit of match upright in the side, and mallet it in, till the box is almost full. The drift for this must be cut flat on one side, to allow for the match. On the top put a very little dry meal powder, or shell-fuse, and press it in with the finger. Cut a piece of double-crown, about an inch broad, and long enough to go rather more than once round the pill-box: paste it all over; lay the pill-box on it, and roll it up; tuck in one end, to make a bottom, and press the other end round the match, and on the meal powder, or shell-fuse, till it assumes the form of fig. 29.
Set the pill-box on a flat surface, put in a very little meal powder or shell-fuse, thensome composition, and mallet it in till full. Roll this up in a piece of double-crown as before; tuck in the bottom, and set by to dry; when dry, put into the other end—the end containing the film of meal or shell-fuse—a piece or two of thin match, and tie it in, as in fig. 30. Dry pill-boxes are best for making chameleon stars; these are half one colour and half another. Make a dozen stars, half yellow and half green, and a dozen more half blue and half crimson; put these into a rocket; they will burst green and crimson, and change to blue and yellow.
The cases are the same as before. To fill them, damp the composition as for Roman candle stars; put a bit of quickmatch into the case, as at fig. 31, and press in the composition. This is usually done with the fingers, but is not very pleasant work, especially with lac solution. A cleaner way, though more tedious, is to fit the case on to a little foot, with a side notch in it, fig. 60; then slightly mallet in the composition. Or a notch may be cut in the side of the box,fig. 61, and the match put in, as fig. 62, and slightly malleted.
Instead of making the cases entirely of writing paper, they may be made half of writing paper and half of coloured double-crown, to indicate the colour of the star.
Another way is to sift a thin layer of French chalk over a sheet of paper, and to roll the stars in it, one by one, as they are punched. When dry, brush off the superfluous chalk, and prime with a bit of match, tied across the mouth.
Pump and drive the stars exactly as for roman candle stars, They may be 31⁄2/8 diameter, and5⁄8long; or they may be formed with figs. 1, 2, and 3, and the side pin of fig. 2 may be removed to c, in which case the stars will be5⁄8diameter, and 31⁄2/8 deep; the former will be an oblong cylinder, the latter an oblate. Cut a strip of red, blue, green, or yellow double-crown, of a suitable breadth, and long enough to go twice round the star. Paste the strip all over, or gum it at the edge only, and lay the star upon it, as at a, fig. 41,with a bit of match behind it; then roll it up and put by to dry. When pasted, it shrinks and holds the match tight; when gummed at the edge this is not always the case; it may then have a piece of thin binding-wire twisted round it. It will have the appearance of fig. 32. In fig. 31, the match is embedded, and dries in the damped composition; in the enveloped stars the stars are dried first, and the match lies outside and blows through. Enveloped stars show well in the air.
The word envelope, as used in these pages, must not be confounded with the same word as applied to the coverings for letters. It is rather synonymous with the term wrapper; you lay an ounce of tobacco on a piece of paper, roll it up and tuck in the ends. So with cases: you roll them up in a piece of paper, and leave an inch vacant at each end to receive quickmatch, &c. This is termed the envelope, that is, the wrapper.
Heads for small rockets may be made of two or three rounds of paper rolled dry, and secured on the inner and outer edges withpaste. After sticking it on the case, which it may be made to fit, as in fig. 36, pinch the top in like a choke, only tight, and tie it round with twine or flax. For coloured rocket heads,6⁄8and upwards, the head may be enlarged by fixing a collar round the top of the case. To make the collar for a6⁄8, roll a case on a9⁄8former, and when dry cut it into short lengths in the lathe, as recommended for pill-boxes; if unprovided with a lathe, saw it with a fine-toothed saw. The advantage of the enlarged head is, that it brings the stars nearer to the rocket, and prevents it from being top-heavy. Another way is to make the heads tapering, and the tops conical, as in fig. 39. One part is rolled on fig. 34, the other on fig. 35; or, a cone may be made of a circular piece of paper, without a former. Cut the circle, along the radius, to the centre; bend it into a cone; secure the edge with sealing-wax, and paste paper over it to overlap the rim: snip the edge with the scissors; paste it inside, and secure it to the other part. But the quickest way of all is to make a long paper bag, which may be made to fit to the greatest nicety. For this purpose take atape-measure; or lay down, on the edge of a strip of writing paper, 7 or 8 inches long, and 1 inch broad, 6 inches, divided into eighths, transferred from a foot-rule. Suppose the6⁄8rocket has a collar, which, on being measured by the paper just alluded to, is found to be 42⁄8inches round; add to this3⁄8for lapping over, making 45⁄8inches. Cut a piece of imperial brown 45⁄8broad, and as long as the case, 6 inches. Make this into a paper bag, 21⁄8inches broad. Be careful that the corners are perfect; a strip of double-crown may be pasted over them. When dry, pinch the mouth open till cylindrical, and merely allow the stars to drop in without forcing them; this will keep the top edge of a wedge shape, fig. 37, and answer the purpose of a cone. If the paper is thin, the bag must be made of two thicknesses; the paper will, then, require to be 9 inches by 6; 43⁄8of this will have to be kept dry, and the other 45⁄8pasted.
A head, made in this way, if required to hold gold rains, or serpents, can instantly be reduced to a cylindrical shape, by pushing the rocket-case right up it, to the top; this will cause the corners to stick out, like twohorns; press them down, and secure them with sealing-wax. Attach a cone, if desired.
Heads made like figs. 38 and 39 may be of three thicknesses of paper, pasted all over.
Fig. 39 shows the manner of tying on the sticks. No variation must be made in their lengths, and it is not advisable to alter their size. To adapt it to the wood, however, a slight alteration might be permitted. For instance, instead of3⁄8square, it might be 21⁄2/8 by 31⁄2/8, a slight increase one way, compensated by a slight diminution the other. It must, however, on no account, be so increased and diminished, as to approach the shape of a lath, as such stick would vibrate, and cause the rocket to quiver. When the heads are a paper bag of the shape of fig. 37, the stick must be tied on, as indicated by the dotted lines.
If the stick is suited to the rocket, it will, when suspended on the finger almost against the mouth, as at f, fig. 40, lie, not quite horizontal, but slightly sloping downward. The wood should be dry pine, free from knots. The sticks are generally cut with a carpenter's cutting-gauge. If the learner has a lathe hewill find a 6-inch circular saw convenient for cutting them.
For amateurs, a6⁄8rocket is a good size; large enough, and small enough. If5⁄8and4⁄8are made, two hollow drifts will be sufficient; for3⁄8, one hollow drift. Very small rockets,2⁄8, are made for children; they are rammed solid, and a hole is pushed up them with a bradawl.
Rockets in former times, before the present days of competition, were charged in moulds. These were of gun-metal, bored truly cylindrical, furnished with hinges, to open and admit the case; they were then screwed up, and might be charged as hard as possible. Names were given them according to the bore of the mould, that is, the external diameter of the cases; a4⁄8was termed an ounce rocket; a5⁄8, a two ounce; a6⁄8a quarter pound; a 71⁄2/8 a half pound; a9⁄8, a pound; a12⁄8, a two pound.
These names were determined by the weight of a leaden ball of the same diameter as the bore. Now a sphere of lead, 71⁄2inches diameter = 90 lbs., or 1440 ounces; consequently one of 15 inches = 720 lbs., similar solidsbeing to each other as the cubes of their like dimensions: the latter sphere being twice the diameter from top to bottom; twice the diameter from left to right; and twice the diameter from front to back; 2 × 2 × 2 = 8.
The external diameter of the rocket being 71⁄2inches, the internal would be 5 inches, and this would be a 90-pounder: hence, for an inch rocket, we have the proportion,
53:1440oz.:: 13:11·52oz.
so that a 12-ounce, or 3-quarter-pound rocket, ought to be a trifle above an inch.
Required the weight of a6⁄8rocket. 5 inches =40⁄8.
403:1440oz.:: 63:4·86oz.
So that a6⁄8is a trifle too large for a quarter-pound.
If, conversely, we require to know the size of a half-pound, or 8-ounce rocket,
1440oz.: 403::8oz.: 3200/9
and ∛(3200/9) = ∛(9600/27) = (∛9600)/3 = 7·08
So, properly, a half-pounder is a trifle over7⁄8. The names in use enable the makers to understand each other, but they are not mathematically correct, and are of no utility to an amateur.
The following table shows the true weight of leaden spheres, the dimensions being taken in inches.
And2⁄3of the above numbers multiplied by 8, give the correct names for rockets in eighths of an inch.
Required the true size of a half-pounder.
(1·328 × 2 × 8)/3 = 7·08.
A trifle above7⁄8, as before stated.
A cast-iron ball 6 inches in diameter weighs 30lb.
Cast iron is about40⁄63the weight of lead.
5280 feet = 1 mile; 3280 feet = 1 kilometre.
Wheel cases may be 55⁄8inches long. Cut the paper, without waste, into 4 strips, each 29 inches long. Fixed cases may be 71⁄4inches long: cut the paper the other way of the sheet, into 4 strips, each 221⁄2inches long. The extra length, for fixed cases, is to allow of their being reported; that is, filled at the end, with an inch, or more, of grain powder, to make a bang like a squib. The cases are to be gauged to the thickness of roman candle cases, but choked like rockets;5⁄8internal, and7⁄8external, are a good size. Two solid drifts will be required for wheel cases; one 51⁄2inches long, besides the head; the other 3 inches: for the fixed cases it will be necessary to have one of 71⁄4inches. They may be turned of box, beech, or ash; but gun-metal drifts are best, though by no means indispensable. If they are cast in gun-metal, they will simply require filing in the rough places. The casesare to be rammed solid throughout, on a foot, fig. 42, turned in one piece, with a nipple, and a pin1⁄3of a diameter thick, and just high enough to keep the choke clear.
In all wheel and fixed cases, whatever the remainder of the fuse may be, begin by putting in one scoop of starting fire; this, when malleted firmly in, should fill about3⁄8of an inch in the case. The subsequent fuse can be selected from the Tables. The choke may be protected with a little clay, before the starting fire, like rockets, if thought desirable: no clay is to be used anywhere else. Wheel cases containing steel-filings are termed brilliant.
To prime the cases, very slightly damp some meal powder, by sprinkling it with a few drops of water; mix and chop it up, or mince it, as it were, with a knife: put a little into the mouth of the case, press the nipple, fig. 42, into it, and work it round; this will prime the choke and the mouth at once, still leaving the choke clear; or, paint the choke and mouth with the sash-tool, with meal paste, just sufficient to wet them, then plunge them into dry meal, give them a rap to shake off the superfluous dust, and lay them by to dry.
Wheel and fixed cases need not be choked at all, but plugged1⁄4of an inch, with plaster of paris, as directed for roman candles. When dry, charge them by setting them flat on the block, without using the foot. Mallet in a scoop of starting fire, then the other. Afterwards, when a number are charged, bore through the centre of the plaster, with a shell-bit,1⁄3the diameter of the case; insert a piece of match in the hole; wash the face of the plaster over with meal paste, and plunge into dry meal. A sheet of double-crown makes 8 wheel case envelopes (2.2.2) 10 by 71⁄2, so that the void at each end, to receive the match, is nearly 1 inch.
It is not possible to devise a formula that will indicate the exact quantity required for wheel cases, as the fuses vary; but, representing the length, in inches, by I; and the diameter in eighths by e, the following will help to serve as a guide.
(I e2)/7 = drams.
Suppose a wheel case 55⁄8inches long, and 4 eighths diameter,
(55⁄8× 4 × 4)/7 =90⁄7= 13 drams.
Suppose a fixed case 71⁄4inches long, and 5 eighths diameter,
(71⁄4× 5 × 5)/7 =181⁄7= 26 drms. = 1 oz. 10 drms.
Gerbes, so called from the French word for wheat-sheaf, which they resemble, are fixed choked cases: they do not show well on wheels. As they contain grains of iron, they must not be under6⁄8; for private exhibitions a good size is9⁄8,9⁄8internal diameter;12⁄8external;3⁄8the diameter of the choke; 111⁄4inches, length of case. Charge the case on a nipple, exactly like a wheel case. It is advisable to put in, first, a little clay, to protect the choke, as the fire, being fierce, would, otherwise, enlarge it, and diminish the ascent of the sparks. Upon the clay drive in a scoop of starting fire, and fill up with gerbe composition. This, when containing iron borings, is termed Chinese fire; the pieces, Chinese trees.
The most magnificent of all, however, is the coloured gerbe. For this, some green, blue, and crimson grains, or small stars must be prepared. They may be quarter-inch cubes, cut as directed for the chopped nitre stars. A far better way, however, of preparing them, is to remove the pin a, of fig. 2, up to c, so that the stars, driven in the tube, will be5⁄8inch diameter, and3⁄8thick. When these are dry, chop them into 4 pieces, by holding a knife, or chisel, across them, and giving it a smart blow with the mallet. They are harder made this way.
To charge the cases: having driven in the clay, and the starting fire, put in 7 or 8 stars, then a scoopful of fuse No. 1 or 2, then 7 or 8 more stars, and another scoop of fuse; mallet the whole 4 layers down firm, with blows not too heavy at a time, but many times repeated. Then put in 7 or 8 more stars, another scoopful, 7 or 8 more stars, and another scoop, and mallet the 4 layers as before; and so repeat. The two layers and the two scoopfuls may fill up, when malleted in,3⁄4of an inch, in a9⁄8case.
Instead of choking the cases, plaster ofparis is far preferable. Let it be3⁄8of an inch thick, and well dried, before charging. After the cases are charged, bore a hole through the plaster,1⁄3of a diameter, that is, with a9⁄8case,3⁄8of an inch diameter. For this purpose it is not necessary to have another shell-bit; bore it with the3⁄16, and enlarge it with a penknife. It is better arched under, till conical, as shown in fig. 48. Prime with 4 or 5 pieces of match, and wash with the sash-tool.
The gerbe being finished, make a cylindrical box, or paper bag, of 2 or 3 thicknesses of paper: fill it with a number of crackers, and a scoopful of meal powder, and fasten it to the gerbe.
No single piece is more effective than a coloured gerbe; the stars will be projected 30 feet, or more: they may be put in, mixed; or, one layer may be blue, another green, another crimson. Twist a piece of wire, deprived of its elasticity, round the neck, and another piece round the bottom, and leave long ends; it can then be fastened by them to the top of a post. To remove the elasticity from iron wire, lay it in the fire tillred hot; withdraw it with the tongs, and put it aside, to cool slowly. If copper wire is used, it will bend without preparation. String must not be employed, as it might burn, and let the case fall. Common pins, patent short whites, deprived of their elasticity, are useful for connecting the parts of lustres together.
These are choked cases, charged with spur fire: the fire is somewhat slow, so the cases must be short: 4 inches long, and5⁄8diameter is a good size. Rub the composition thoroughly up in the mortar; the vegetable black produces beautiful star-like sparks, totally dissimilar to any other. Put a little composition, at a time, into the case, and jolt it with the roman candle rammer.
Vegetable black, introduced into a star, causes it to tail, like linseed oil. Light such star on the hob; it will burn, and leave a residue, unaltered in shape; blow upon this continuously with the mouth, or, better still, with a pair of bellows: the supply of oxygenwill cause it to boil up, in a state of fusion, when it will begin to throw out clusters of the peculiar starlike sparks, before mentioned, bright and yellow as new sovereigns.
Vegetable black is a pure lamp black; some samples of lamp black make equally good stars, but others are worthless. Greater reliance can be placed upon vegetable black. Vegetable black and lamp black must not be mixed with linseed oil, as such mixture is liable to spontaneous combustion.
Roll up a tube for pill boxes, of two thicknesses of brown paper. When dry, cut it into pieces about 11⁄8inch long: choke one end, like a wheel case; set it on a nipple,and charge it with spur fire, till full within1⁄16of an inch: fill up flush with a little plaster of paris, pressed in flat with a knife: prime the choked end, and put a number of such cases into a rocket head, or shell.
These are unchoked cases, like roman candles; 6 inches long,3⁄8internal, 41⁄2/8 external, is a good size. They should be rammed,as hard as possible; and, for this purpose, it is best to have a mould. Now, if a case is rolled of such a size that it will exactly fit into a brass tube, and is charged, in it, very hard, it will swell, and it will be almost impossible to get it out again; but if it be made a trifle smaller, so as to just slip through the tube; then, if a piece of writing paper be rolled, dry, round it, once or twice, so as to make it a tight fit, and the case is charged, it can be pushed out, like a pellet from a popgun, leaving the writing paper, generally, in the tube, or mould, and the case will come out without a wrinkle.
Let the composition be put in, very little at a time, and well driven with a solid rammer and mallet. Fig. 59 represents the mould; the foot b fits the tube a; the tenon c fits the case; a wire, d, goes through 2 holes in the brass tube, and a hole through the foot; a nut, e, to keep the wire from jarring out, is made of a piece of indiarubber: make a hole through it, with a bradawl, and slip it on the wire; or, a screw-eye may be passed through and held with a leaden, or wooden nut.
A tourbillion, so called from the French word for whirlwind, is a case made to rotate and ascend at the same time, forming a spiral of fire, and ending in the shape of an umbrella.
Roll the case like a roman candle case, but gauge it to the thickness of a rocket case. Let the inner diameter be6⁄8; the outer9⁄8; the length of the case 71⁄4inches, fig. 43. To charge the case, have a mould, as directed for port-fires; and let the tenon rise exactly3⁄8of an inch up the case. Put in a little composition at a time, and mallet it as firmly as possible, till within exactly3⁄8of an inch of the top of the case; so that there will be a vacancy of3⁄8of an inch, at each end. Fill each of these ends flush with plaster of paris.It is, better, too, if you can manage to fill the middle half-inch of the case with plaster of paris. It can be effected with care, and will hold the screw, hereafter to be described, more firmly.
Construct a wooden box, fig. 44, consisting of a bottom and two sides only, firmly screwed together. Each of the pieces of wood is to be 71⁄4inches long, and1⁄2an inch thick. The internal breadth of the box is to be exactly9⁄8of an inch; and its internal depth exactly 41⁄2/8 or9⁄16, so that when the tourbillion is laid evenly in it, and pressed down to the bottom, half of the case will be in it, and half out of it. At a point b, fig. 44, on the top of the side, half an inch from a, make an ink mark: and, at a point d, half an inch from c, make another ink mark. Fig. 45 is the bottom of the box. At a point w,5⁄8of an inch from the end; and, at a point z,5⁄8of an inch from the other end, make holes with a fine bradawl, truly, in a line down the middle of the wood, as between side and side. The distance w z is 6 inches; divide it into 3 equal parts, in the points x and y, two inches asunder. Bisect x y in the point s. Procure 5 carpetpins, fig. 47: they will, probably, be3⁄4of an inch long. Drive them through the holes w, x, s, y, z, inverting the box for the purpose, so that they shall stand bolt upright in the box. Now screw, or nail a piece of wood over the bottom of the box, entirely to cover it, to prevent the carpet pins from getting displaced. It will be seen, that, if the tourbillion be now laid evenly in the box, and pressed down till it rests on the bottom, the projecting pins will make 5 holes, in the under part of the case. While it is thus lying, with a stiletto, such as used by sempstresses, for making eyelet holes, prick the side of the case over the line b, of fig. 44; and, also, over the point d. There will now be 7 holes; 5 underneath, 1 to the right, and 1 to the left: the latter are the places for the whirlers, or holes of rotation: 4 underneath, for the lifters, or holes of ascension; the centre one, s, receives a nail or screw. Take a bradawl, fig. 49,3⁄16of an inch diameter; and slip over it a shield, consisting of a piece of wood with a central hole up it, like a pop-gun, of such a length, that, when it is slipped on, only1⁄4of an inch of thebradawl protrudes; or, instead of a bradawl, fix in a handle, a wire of equal length, namely1⁄4of an inch, and file it to a point. Push this into all the holes, except s, making 4 holes underneath, and 2 horizontal holes, one left, one right: all these holes will be exactly of the same depth, on account of the shield: see that they are bored perfectly true, the horizontals exactly 90 degrees above the others, or1⁄4of the circumference.
The next thing required, is a piece of hooping, or curved stick, about6⁄8of an inch broad, and as long as the case, 71⁄4inches. In the centre of this, bore a hole, and countersink it; then, with a screw, an inch and a quarter long, screw the hooping, at right angles, on the bottom of the case, through the point s of fig. 45, which must be enlarged to receive the screw. A touch of glue may still farther hold the wood in position. It will now assume the shape of a cross, like figs. 50 and 51. Fig. 50 shows the under side of the case; fig. 51 the upper. From w to x lead a bit of naked match; push the ends into both holes, and secure with a little wetted meal, pressed in with a knife. Do the same withy and z. Paste a piece of double-crown,3⁄4of an inch broad, and of sufficient length, and cover each of the two pieces of match, with two layers of the paper. Turn it over, like to fig. 51; connect the holes a and b with a bit of naked match; and, under the centre of it, slip another piece of naked match, having a piece of touch-paper round the protruding end: cover the match with two thicknesses of pasted paper, in the same manner as the under holes. The tourbillion is now complete. See that it will balance, and swing round easily, when laid upon a level surface. The proper way to fire it, is from a flat sheet of iron, or a flagstone. Light the touch paper; the fire will communicate to the side holes, and set it in rotation. As soon as1⁄8of an inch of fuse has burnt from each end, and the piece has got well into action, the 4 under holes will catch, and cause it to ascend.
Instead of this mode of making a tourbillion, some charge it with an inch of solidly rammed clay, in the middle; fasten the stick, by crossing it with binding-wire; bore a hole through the middle of it, and of the clay, and slip it over a tapering-wire, standingupright in a block, like the spindle of a rocket. Four holes only are then used; two of rotation, and two of ascension; and the whole are fired at once, the match starting from one of the under holes, going to the side hole; over, across, to the other side hole, and on to the other under hole.
Instead of making them with clay in the middle, there is yet a better method of having two cases, each about 4 inches long; and gluing, or fastening them with tin-tacks on a centre-piece, turned with a tenon at each end, fig. 52; two balancing arms, one on each side, must then be fixed to the centre-piece.
In a windmill, as is well known, the vanes, or sails, are set at an angle. There is a toy, made of two slips of tin, forming a cross, and set at an angle, sloping upwards, called the flying dutchman; this, when spun with a string, from a handle like a humming-top, flies up into the air, on escaping from the string. Steel Fliers, with two vanes, are used by sportsmen to practise shooting flying. Small balloons, some years ago, in a room in the Polytechnic Institution, free from a current of air, were guided or driven by asimilar contrivance, moved by clockwork. The screw-propeller of a ship acts on the same principle. I think it possible that, if two vanes were fixed in the central piece of wood, set at an upward angle of 10, 15, or 20 degrees from the horizontal, they might assist the ascension, and so cause the tourbillion to reach a greater height; or, the vanes alone might cause it to rise, upon 4 side holes, two to the left, and two to the right, causing it to rotate. The design is shown at fig. 54, the shape of the vane at fig. 53. I have not yet tried it, so offer it only as a suggestion.