Part 14
If you want a former round which to make the case, _or mortar_, as it is called, of the two and a-half inch size, you can generally find one ready made at the draper’s. They have them as rollers for silks, &c., and the above is one of their sizes. I have found one of these very convenient.
In the next place you must always keep your eye on the look-out for old odd pieces of thick brown paper, or sugar paper, or any thick paper used for parcels, and turn them to account; any old pieces of cardboard may also be worked in. You will want a case or mortar _seven inches long_, and so well pasted and closely rolled that you can hardly bend it with your fingers. Do not spare the paste, nor imagine that you can dispense with the roller board. Well paste the former and all the paper, and when you have finished the mortar, set it by, and do not use it till it is thoroughly dry and hard, but at the same time do not attempt to hurry the drying over, and so warp it and put it out of shape.
You will now have a round hard cylinder of pasteboard, open at both ends. Cut a piece of deal or other wood, of a size that will fit tightly into one of these ends, and _about an inch thick_, and glue it in, to make a firm bottom to the mortar, so that it has no chance of coming out.
Now weigh out one-ounce of common gunpowder; such as is sold at the shops at about 1s. per pound is quite good enough for this purpose. Put this into a piece of _thin_ paper, and make it up into a neat little flat circular parcel as shown at fig. 105. It should be as nearly as possible the same size as the interior of the mortar. You will find that the mortar of the two and a-half inch size is capable of holding about twenty-eight serpents. But, whatever sized former you use for the mortar, ascertain how many serpents will be required to fill it, remembering that they are by no means required to fit in tightly; that if they are fitted in tightly your mortar is pretty sure to be blown to pieces, which catastrophe is by all means to be avoided. Having ascertained the number of serpents required, tie them into a bundle with cotton. This will enable you to pass them without any trouble into the mortar. But before putting them in take out the centre serpent, and tie to its neck a piece of quick-match in the manner represented in fig. 106. This match is to convey the fire to the mouths of the serpents, and so on to the packet of powder. When the piece of match has been attached as directed above, replace the serpent in the midst of the bundle. Take notice that that part of the match which projects beyond the mouth of the serpent _is to be uncovered_—that is, is to have its case cut away from it.
Now in order to insure the proper lighting of all the serpents, I have adopted a plan which I have always found successful. The usual plan is to smear the flat side of the packet of gunpowder with meal-powder-paste, and to let the serpents stand mouth downwards upon this. I am well aware that many good mines are made in this way, but I must think that their success is the result rather of chance than of anything else. I have experimented a great deal in this direction. I have fired mines so prepared in a place where I have been able to pick up the remains of the serpents after the explosion of the mines, and I have frequently found serpents that had never taken fire at all. And this fact set me to work upon discovering some new plan. I at once hit upon the cause of former failures, imagining them to be due to the too rapid ignition of the powder, which had not allowed time enough for the fire to be conveyed to the mouths of _all_ the serpents. In attempting to rectify this, I naturally enough ran to the other extreme, and gave them rather too long a time, so that they actually found their way out of the mortar by their own force, and the powder expended itself in a mighty puff just when they were out of the reach of its influence. Of course the serpents only found their way just out of the mortar, and did not produce that lively effect in the air which was intended. So then I had recourse to the plan which I now adopt, and which has never failed me. I take some circles of thin blue paper—such paper as the pyrotechnists use for making into touch-paper, which is called _thin blue double crown_; these circles I cut of such a size that they will just pass into my mortar, and I smear them well over with meal-powder-paste made with meal-powder moistened with thin starch or gum-water. One of these circles I place between the packet of powder and the mouths of the serpents. And I find that this arrangement just allows time enough for the fire to be conveyed to all the serpents before the packet of powder is exploded.
You will now have the three principal parts of the mine ready to put into the pasteboard mortar. In order to do this, take your bundle of serpents and hold them _mouths upwards_, as represented at fig. 107, and on their mouths lay the primed circle of thin paper, _meal-powder side downwards_. On this lay the packet of gunpowder, with its _smooth side downwards_, and its tied side upwards. Then taking the mortar, _bottom upwards_, pass it over the whole in the way in which an extinguisher is used. The mine, thus far completed, is now to be turned the proper way upwards, and a knife or pair of scissors passed into it to divide the cotton which bound the serpents together. Care must be taken that this little piece of after-work is not forgotten and left undone, otherwise your serpents will come out in a lump, and will not be able to spread.
But now we come to the case which is to play before the mine is fired. This may be a short case of the one-ounce or two-ounce size, and may be filled with the beautiful old composition called spur-fire. The composition for this is—
Nitre 18 parts. Sulphur 8 „ Lampblack 6 „
But there is a great deal of art in preparing this composition. The ingredients require to be well-sifted together, and then rubbed together in a large mortar with a wooden pestle. You must have two or three short choked cases ready while this pestle and mortar operation is going on, in which to try the composition at different stages of its progress. If the ingredients have not been sufficiently rubbed with the pestle, very few of the beautiful spur-shaped sparks will be thrown out. But if, on the other hand, too much rubbing has taken place, the composition will burn too fiercely, and will throw out only drossy sparks. There is certainly a good deal of patience necessary in the preparation of this spur-fire composition, but when properly made it will repay you for all the trouble it has given. It is better to make a good large batch of it at a time. It is said to improve after being rammed into cases a long time.
There is only one disadvantage that I have ever found in this spur-fire, and that is, that much of its beautiful effect is lost unless the spectators are very close to it when it is fired. The scintillating sparks may be caught in the hand without danger.
But there are many other compositions which will answer very well for the beginning case for a mine. For instance, you may use—
Meal-powder 2 parts. Steel filings 1 part.
Or,
Meal-powder 2 parts. Iron borings 1 part.
Or,
Meal-powder 4 parts. Charcoal 1 part.
These compositions may be rammed into either one-ounce or two-ounce cases, and primed in the ordinary way. The tail end of the case must be left open, in order to insert the end of the match which comes out of the bundle of serpents.
You will next require a circular piece of millboard, of a size that will answer as a lid to your pasteboard mortar. Through the centre of this lid bore a hole with a centre-bit just the size of the case that you mean to insert; and when you have decided how far this case shall project out of the lid, make a mark, and glue the case into the central hole: and when you have made the necessary connection between the tail of the fountain-case and the quick-match from the bundle, the lid is ready to be pasted on. If, however, there is any chance of the mine being knocked about before it is fired, fill in the space above the serpents with waste paper, or, still better, with common wadding, _which does not burn_.
It only remains now to paste a strip of thin paper neatly round the top of your mortar, so as to secure the lid, and then to put some touch-paper to your fountain-case, and the piece is ready for firing.
There is another way of making these mines which you can adopt if you please. Instead of using a short fountain-case, a long one is employed which will reach down to the smeared meal-powder pad. This case has, of course, to pass through the bundle of serpents, and so takes up a good deal of room among them. If you employ a long case of this kind, you will find it best to use one of the sparkling compositions given above, _and not the spur-fire_; or, at all events, if the spur-fire is used, only half fill the case with it. It is a slow-burning composition, and answers much better in _short_ cases of large calibre than in long cases of small bore.
For a mine two inches in diameter the charge of powder should be three-quarters of an ounce. The mortar should be about six inches high.
For a mine two and a-half inches in diameter, and seven inches high, the charge of powder should be one-ounce.
For a mine three inches in diameter, and eight inches high, the charge should be an ounce and a-half.
But I must now proceed to tell you of another way of making mines for exhibition purposes which can be fired at any given moment. These are fired from iron mortars. One of these mortars will last a lifetime. The size that I use is that which has a diameter of three inches. The mortar is made of thick sheet-iron, rivetted firmly into the form of a cylinder, with an iron ring round its mouth, and a wood block screwed into its other end for a foot. This mortar has a clear depth of eight inches inside, and is capable of throwing three dozen serpents. The exterior of the iron cylinder is bound round with cord, which is supposed to give it great additional strength. So much for the mortar from which these exhibition mines are fired. The serpents, powder, &c., are contained in paper bags, and have a projecting piece of match by which they are fired. I have a solid cylinder of wood, six inches long, and two and three-quarter inches in diameter, upon which I make my paper bags for these mines. A former of this size makes a bag that will contain the three dozen serpents, and will at the same time pass easily into the mortar. The powder, meal-pad, serpents and quick-match are to be put in precisely in the same manner as that directed above: the powder packet at the bottom, of course, then the meal-pad, then the serpents. After all are inclosed, feel with the fingers for the string that ties the serpents together, and cut through the paper of the bag and this string to liberate them. Your mine will then be ready for firing. Any number of these bags can be fired one after another from the same iron mortar.
You will find a sketch of a pasteboard mortar at fig. 108, showing its contents and the fountain-case. You will find also a sketch of an iron mortar, fig. 109, and bag and serpents, fig. 110; such as I use, which is by far the most convenient way of exhibiting serpent mines.
CRACKER MINES.
68. We will now proceed to speak of cracker mines, another very effective item in exhibition pyrotechny. With regard to the crackers that are employed for this purpose, I cannot think that you will economise at all by trying to make them yourselves. In order to make them all of one uniform size and shape—and these points must be attended to particularly in the manufacture of crackers for mines, otherwise you will be unable to pack them properly in the bags or mortars—a considerable amount of apparatus of rather an expensive kind is required, and is in fact indispensable. The money laid out in the purchase of this apparatus would furnish you with many grosses of mine crackers. If you will be advised by me, you will purchase them of Mr. Darby, whose crackers for this purpose are, in my opinion, exceedingly good. The only difference between mine crackers and those usually sold at the shops for the 5th of November is in their _priming_. Instead of having touch-paper, at which they are lighted, a piece of bare quick-match is left projecting from the mouth, which, of course, takes fire very readily.
[Illustration: [Fleuron]]
The mortars used for throwing crackers differ from those employed for throwing serpents in being square instead of round. I shall speak only of one size of cracker mortar, because you can at your pleasure fire from it any number of crackers from one dozen to four dozen by adopting my plan of packing them. If you are about to use a pasteboard mortar, you must have a square former made, two inches and three-quarters square and six inches long. Upon this former make a very strong mortar with well-pasted cardboard and thick paper, and let it be thoroughly dry before you use it. Glue into one end of it a piece of wood an inch thick for a bottom.
You will now require just the same kind of packet of gunpowder as was spoken of under the head of serpent mines. This packet may contain an ounce and a-half of common powder. Put it into the bottom of the mortar, flat side upwards; then put a piece of thin paper, smeared over with meal-powder paste, meal-powder side upwards, and then proceed to put in your crackers in the following way:—You will find two dozen a very good number for cracker mortars of this size. I frequently use _three_ dozen, but this is not necessary. I will suppose that you have determined to use two dozen. Take _six_ of these; pack them side by side, so that their primed mouths are arranged in a line; tie them in this position with a piece of cotton; make four of these packets containing six crackers; now put them into the mortar in such a way _that the projecting pieces of quick-match are all turned inwards_, as shown in the drawing at the page of illustrations. The crackers will, of course, all be lying on their sides. Now down the centre of this arrangement lay three or four pieces of bare quick-match, which shall be in immediate juxtaposition to all the primed mouths of the crackers, and which shall reach down to the meal-powder pad. Thus you will infallibly insure the lighting of all the crackers before the charge of powder takes fire at the bottom.
Over this mine, and as an introduction to it, you can, if you please, place a fountain-case, as with the serpent mines, gluing it into the centre of the lid of the mortar, and connecting its tail end with the crackers below.
But the most useful plan for exhibition purposes is to have an _iron_ mortar for these mines, made about two inches and three-quarters square (interior measurement), and six inches in depth. Iron mortars should have a very substantial foot of wood. If an iron mortar is employed for cracker mines you must have a wooden former made, about two and a-half inches square and six inches long, on which to form the paper bags that are to contain your powder, crackers, &c. The arrangement of the contents of these bags is precisely the same as that recommended for the filling of the _pasteboard_ cracker mortars, except that of course a piece of quick-match must be left projecting from the top of the bag by which the whole is fired. Take especial notice that after placing the parcels of crackers in the bags, as directed above, the cotton which binds each parcel must be cut so as to liberate the crackers, otherwise you will have four parcels of crackers instead of twenty-four crackers making their appearance at the explosion of your mine.
In the page of illustrations, fig. 108 represents a section of a pasteboard serpent mine; _aa_, the fountain-case; _bb_, the serpents; _c_, the meal-pad; _d_, the packet of powder; _ee_, the match passing from the fountain-case through the bundle of serpents; _f_, the wooden block at the bottom of the mortar; _gg_, the lid. 109 represents an iron serpent mortar. 110 represents a mine bag for firing from an iron mortar. 111 represents the arrangement of crackers in a cracker mine. The drawing will be found about the right size, and crackers packed in this manner cannot fail to light.
FIVE-POINTED STAR.
69. The cases are made upon the same “former” on which the quarter-pound rocket-cases are rolled. They consist of a piece of 70-lb. brown paper and a piece of imperial board. The sheet of brown paper is cut into strips, as represented in the annexed diagram, by which it will be seen that each sheet furnishes enough paper for _six_ cases. The imperial board should be divided, as shown in the following sketch, 112, into twelve equal strips—thus: so that two sheets of 70-lb. brown paper and one of imperial board will give material for one dozen cases for five-pointed stars. The paper and board must be well pasted, and the rolling board used unsparingly, as cases for this purpose cannot be too strong and hard.
[Illustration:
Fig. 112. ]
[Illustration:
Fig. 113. ]
The common plan for filling these cases with composition is simply to put them on the same settle on which quarter-pound tourbillons are rammed, and to drive into the lower end of them about half-an-inch of clay, very solid, and to ram in the composition upon this until it rises to such a height as will enable the star to burn as long as the piece or pieces with which it has to keep time. But I think a much better plan is the following:—Procure a turned drift of box, or some _hard_ wood, about five inches long in its straight part, with an end as represented at fig. 113. Put a ladleful of clay into the case when it is upon the settle (the ladle used for filling quarter-pound rockets is meant), and drive down the clay with the conical end of the drift, by which means you will have a hollow clay cone formed in the end of the case. Now ram in your composition, which may be made from either of the following formulas:—
FOR FIVE-POINTED STARS. No. 1. Nitre 16 parts. Sulphur 6 „ Meal-powder 4 „ Antimony 2 „
No. 2. Nitre 16 „ Sulphur 8 „ Meal-powder 6 „ Antimony 4 „
No. 3. Nitre 16 „ Sulphur 8 „ Meal-powder 4 „ Antimony 3 „
It will be best to decide first of all which of these compositions you prefer, and to keep to that, remembering that five-pointed stars are never used singly, but only as parts of compound pieces, and that, in order to produce their proper effect, they ought to last just for a certain time and no longer. By keeping to _one_ of the compositions given above, you will be able to time them better. I cannot give any directions for the quantity of composition to be driven in—this must depend entirely upon the part which it is intended that the stars should play in the piece for which they are made, and can be decided only by actual experiment. The composition will not require to be driven very hard.
You will by this time be beginning to wonder how a case filled in the manner described above is to make a five-pointed star. Well, there is no great difficulty in achieving this end. Provide yourself with a gimlet which will make a hole about one-eighth of an inch in diameter, or rather more; also with a pair of compasses the legs of which can be secured at certain distances from one another. Let the points of the compasses be exactly such a distance apart that they will represent _one-fifth of the exterior circumference_ of the case—that is, so that they will exactly go round the case in five strides, finishing at the point from whence they started. When you have thus adjusted your compasses, make them perform their five-stage journey _round that part of the case inside which is the hollow clay cone_, about half-way between the point and base of the cone, and wherever the points of the compasses touch, there make a mark by pressing the point into the case. You will thus have divided the circumference of the case into five equal parts. Now at each mark made by the compasses bore a hole gently with your gimlet, which should be a sharp one, taking care that you only bore through the case and the clay, and disturb the composition as little as possible. In order to prime the case, fill the hollow at the end of it, which was occupied by the top of the settle, with wetted meal-powder, and when this is dry, pass across it a piece of bare quick-match, the ends of which should be long enough to be tucked into two of the gimlet-holes, and which will convey the fire from the priming to the composition inside the case. Then cut some pieces of thin paper (such as double crown) three inches wide, and long enough to go twice round the case, and paste one of these on the case just below the gimlet-holes, so that the paper covers up gimlet-holes, priming, match, and all, and projects an inch and a-half or thereabouts beyond the primed end of the case. This projecting paper serves to contain the end of the encased match which is to connect the five-pointed star with other pieces.
The best method of fixing these stars on the frames for which they are required is to have projecting from the frames wooden pegs of such a size that the unprimed end of the case can be squeezed tightly over them or glued on to them. I should have stated that when the proper amount of composition has been inserted, a little clay should be driven on the top of it for the sake of security, and there should be not less than three-quarters of an inch of unoccupied case beyond this clay. Into this unoccupied space the pegs mentioned above should be fixed.