CHAPTER VIII.

Chapter 397,440 wordsPublic domain

OF SUNDRY FIRE-WORKS, DENOMINATED AIR-WORKS.

Before we notice the various kinds of wheel-works, and their appendages, we purpose to consider the formation of gerbes, air-balloons, mortars, bombs, tourbillons, aigrettes, and some other works.

_Sec. I. Of the Composition and Mode of forming large and small Gerbes._

In preparing cases for gerbes, it is necessary that they should be made strong; as they would be liable to burst, on account of the strength of the composition, which comes out with great velocity. They should be of the same thickness at top and bottom, and the paper well pasted. Their necks should be long, in which case, the iron would have more time to be heated, by meeting with more resistance in its disengagement, than if the neck was shorter; for then it would be burnt too wide before the charge was consumed. Long necks will throw the stars to a greater height, which will not fall before they are spent. They should rise and spread in such a manner as to resemble a wheat-sheaf.

Gerbes are generally made about six diameters long, from the bottom to the top of the neck. Their caliber must be one-fifth narrower at top than at bottom. Their neck is one-sixth diameter, and three-fourths long. There is a wooden foot or stand, on which the gerbe rests. This may be made with a choak or cylinder, four or five inches long, to fit the inside of the case, or with a hole in it to put in the gerbe: both these methods will answer the same end. In the charging of gerbes, there will be no need of a mould, the cases being sufficiently strong to support themselves. Before this operation is commenced, we must be provided with a piece of wood made to fit in the neck. If this precaution is not used, the composition will fall into the neck, and occasion a vacancy in the case, which will inevitably burst it, the moment the fire reaches the air. A weak composition should be put in at first, to the quantity of one or two ladles full. After the case is filled, take out the piece of wood, and fill the neck with slow charge.

Small gerbes, or white fountains, as they are sometimes called, are usually made of four, eight, or sixteen ounce cases, of any length, taking care to paste, and otherwise make them very strong. Before they are filled, however, drive in clay one diameter of their orifice high. When filled, bore a hole through the centre of the clay to the composition. The ordinary proportion will answer for the vent, which must be primed with a slow charge. Large gerbes are made by their diameters, and their cases at bottom one-fourth thick. The interior diameter of a gerbe is found, by supposing the exterior diameter of the case, when made, to be five inches, by taking two-fourths for the sides of the case, and there will remain two and a half inches for the bore.

Gerbes produce a brilliant fire, and appear remarkably beautiful, when a number of them are fixed in front of a building.

The composition of gerbes is similar to that of the Chinese fire. It is to the cast-iron, which enters into it, that its beautiful effects are to be ascribed. In fact, the composition of Chinese fire differs considerably, as we shall notice, when we treat of it, according to the purpose for which it is employed. It is adapted, for instance, in various proportions of its constituent parts, to calibers of different diameters, cascades, representation of palm trees, as well as for large and small gerbes. The old formula for gerbes is the following.

_Composition for Gerbes._

Meal-powder, 6 lbs. Beat cast-iron, 2 lbs. 1½ oz.

The present formula, as we remarked when speaking of compositions for calibers from three-quarters of an inch to an inch, is saltpetre 1 oz, sulphur 1 oz, meal-powder 8 oz, charcoal 1 oz, and pulverized cast-iron 8 oz.

The vivid and rapid combustion which ensues, when this composition is inflamed, cannot be accounted for in any other way, than that the nitre is acted upon by the sulphur, the charcoal, and the iron; that the gunpowder, during its combustion, raises the temperature to the degree necessary for the decomposition of the nitre by the substances mentioned; that sulphurous and probably sulphuric acid, as well as carbonic acid, are generated, by the union of the sulphur and carbon with a part of the oxygen of the nitre; that the iron undergoes a combustion, both in contact with the nitre and with atmospheric air; and, lastly, that the _effect_, which characterizes this composition, and other similar compositions, into which cast-iron enters, as in the celebrated Chinese fire, is to be attributed to the iron; and the appearance which iron assumes, when in a state of combustion, is owing to no other cause than its rapid combination with oxygen, by which the metal is oxidized. (See _Iron_, in _Part_ I.)

_Sec. II. Of Paper Mortars._

It may not be improper, in this place, to give the manner of forming paper mortars. These mortars are necessary for a variety of exhibitions, as will appear hereafter.

Mortars are made of stout paper; or several sheets are pasted together, and made into pasteboard, in the manner before described. (See _Pasteboard_.) The preparations are various according to the size required. For a coehorn mortar, which is 4 inches and 2/5ths in diameter, roll the pasteboard on the former, on which it is made, 1/6th of its diameter thick, and, when dry, cut one end smooth and even; then nail and glue it on the upper part of the foot. Afterwards cut off the pasteboard at the top, allowing for the length of the mortar, two and a half diameters from the mouth of the powder chamber.

The mortar is then bound round with a strong cord, wetted with glue. The bottom of the foot, it being turned out of elm, is one diameter and two thirds broad, and one diameter high, and the part which goes into the mortar is two-thirds of its diameter in height. The copper chamber for the powder, which is separate from this, is made in a conical form, and is one-third of the diameter wide, and one and a half of its own diameter long. In the centre of the bottom of this chamber, make a small hole, a short distance down the foot; this hole must be met by another of the same size, made in the side of the foot. If these holes are made true, and a copper pipe fitted into both, the mortar, when loaded, will prime itself; for the powder will naturally fall to the bottom of the first hole. By putting a piece of quick match to the side, it will be prepared for firing.

When mortars of a larger size than ten inches in diameter are required, it is better to have them made of brass. See further observations on this subject in section seventh of this chapter, in the article on _fire-pots_.

_Sec. III. Of Mortars to throw Aigrettes, &c._

Shells are filled with a variety of pyro-preparations, as stars, rains, serpents, &c. These are put in first, and then the blowing powder, as it is called; but the shells must not be quite filled. They must be introduced into the shells through the fuse hole. Some substances, however, as marrons, being too large to go through the fuse hole, must be put in before the shell is closed. When the shells are loaded, glue and drive in the fuses very tight. With respect to the diameter of the fuse hole; for a coehorn balloon, let the diameter be seven-eighths of an inch; for a balloon, five and a half inches in diameter, make the fuse hole one inch and one-sixth in diameter; for an eight-inch balloon, one inch and three-eighths; and for a ten-inch balloon, one inch and five-eighths.

Air-balloons are divided, according to the substances they contain, or the effect they are to produce, and are usually of four kinds; namely, 1. Illuminated air-balloons, 2. Balloons of serpents, 3. Balloons of reports, marrons, and crackers, 4. Compound balloons. Balloons and shells, in fire-works, are the same.

In the following view of the different balloons, we have given the number and quantity of each article for the different shells, designating their kind and character:

_Coehorn balloon Illuminated._

Meal-powder, 1½ oz. Grain, do. ½ -- Powder for the mortar, 2 --

Length of the fuse composition, three-quarters of an inch: 1 oz. drove or rolled stars, as many as will nearly fill the shell.

_Coehorn balloon of Serpents._

Meal-powder, 1½ oz. Grain, do. ½ -- Powder for the mortar, 2¼ --

Length of the fuse composition 13/16ths of an inch: half-ounce cases, driven three diameters, and bounced three diameters, and half-ounce cases, driven two diameters and bounced four diameters, of each, an equal quantity; and as many of them as will fit in easily, placed head to tail.

_Coehorn balloons of Crackers and Reports._

Meal-powder, 1¼ oz. Grain, do. ¾ do. Powder for the mortar, 2 do.

Length of the fuse composition 3/4 of an inch; reports 4, and crackers of six bounces, as many as will fill the shell.

_Compound Coehorn Balloons._

oz. dr. Meal-powder, 1 4 Corn, do. 0 12 Powder for the mortar, 2 4

Length of the fuse composition 13/16ths of an inch: 1/2 oz. cases driven 3-1/2 diameters, and bounced 2, 16; 1/2 ounce cases driven 4 diameters and not bounced, 10; rolled stars, as many as will complete the balloon.

_Balloons illuminated (Republican)._

oz. dr. Meal-powder, 1 8 Grain, do. 0 12 Powder for the mortar, 3 0

Length of the fuse composition 15/16ths of an inch; 2 oz. strung stars, 34; rolled stars, as many as the shell will contain, allowing for the length of the fuse.

_Balloon for Serpents, (Republican)._

oz. dr. Meal-powder, 1 Grain, do. 1 8 Powder for the mortar, 3 8

Length of the fuse composition, 1 inch; 1 oz. cases driven 3-1/2 and 4 diameters, and bounced 2, of each an equal quantity, sufficient to load the shell.

_Balloons with crackers and Marrons. (Rep.)_

oz. dr. Meal-powder, 1 8 Corn powder, 1 4 Powder for the mortar, 3

Length of the fuse composition 14/16ths of an inch; reports 12; to be completed with crackers of 8 bounces.

_Compound balloons (Republican)._

oz. dr. Meal-powder, 1 5 Corn powder, 1 6 Powder for the mortar, 3 12

Length of the fuse composition, one-inch; 1/2 ounce cases driven and bounced 2 diameters, 8; 2 oz. cases filled 3/8ths of an inch with star-composition, and bounced 2 diameters, 8; silver rain falls, ten; 2 oz. tailed stars, 16; rolled brilliant stars, 30. If this should not be sufficient to load the shell, it may be completed with gold rain falls.

_Eight-inch balloons Illuminated._

oz. dr. Meal-powder, 2 8 Grain powder, 1 4 Powder for the mortar, 9

Length of the fuse composition, one inch and 1/8th; 2 oz. drove stars, 48; 2 oz. cases, driven with star composition, 3/8ths of an inch, and bounced 3 diameters, 12; and the balloon completed with 2 oz. drove brilliant stars.

_Eight-inch Balloons of Serpents._

oz. dr. Meal-powder, 2 0 Corn powder, 2 0 Powder for the mortar, 9 8

Length of the fuse composition, 1 inch and 3/16ths; 2 oz. cases driven one and a half diameters, and bounced 2, and one-ounce cases driven 2 diameters, and bounced 2-1/2; of each an equal quantity, sufficient for the shell.

We may remark, that the star composition, driven in bounced cases, must be managed in the following manner: First, the cases must be pinched close at one end, then the corn-powder put in for a report, and the case pinched again close to the powder, only leaving a small vent for the star-composition, which is driven at top, to communicate to the powder at the bounce end.

_Compound eight-inch Balloon._

oz. dr. Meal-powder, 2 8 Corn powder, 1 12 Powder for the mortar, 9 4

Length of the fuse composition, 1/8th of an inch; 4 oz. cases, driven with star composition, 3/8th of an inch, and bounced 3 diameters, 16; 2 oz. tailed stars, 16; 2 oz. drove brilliant stars, 12; silver rain falls, 20; 1 oz. drove blue stars 20; and 1 oz. cases driven and bounced, two diameters, as many as will fill the shell.

_Another of eight-inches._

oz. dr. Meal-powder, 2 8 Corn, do. 1 12 Powder for the mortar, 9 4

Length of the fuse composition, 1 inch and 1/8th; crackers of six reports, 10; gold rains, 14; 2 oz. cases driven with star composition, 3/16ths of an inch, and bounced 2 diameters, 16; 2 oz. tailed stars, 16; 2 oz. drove brilliant stars, 12; silver rains, 10; 1 oz. drove blue stars, 20; and 1 ounce cases, driven with brilliant charge, 2 diameters, and bounced 3, as many as the shell will hold.

_A compound ten-inch Balloon._

oz. dr. Meal-powder, 3 4 Corn powder, 2 8 Powder for the mortar, 12 8

Length of the fuse composition 15/16ths of an inch; 1 oz. cases driven and bounced 3 diameters, 16; crackers of eight reports, 12; 4 oz. cases, driven 1/2 an inch with star composition, and bounced 2 diameters, 14; 2 oz. cases driven with brilliant fire 1 and 1/4th diameters, and bounced 2 diameters, 16; 2 oz. drove brilliant stars, 30; 2 oz. drove blue stars, 3; gold rains, 20; silver rains 20. After all these are put in, fill the remainder of the case with tailed and rolled stars.

_Ten inch balloons of three charges._

oz. dr. Meal-powder, 3 0 Corn-powder, 3 2 Powder for the mortar, 13 0

Length of the fuse composition, 1 inch: the shell must be loaded with 2 oz. cases, driven with star composition 1/4th of an inch, and on that one diameter of gold-fire, then bounced three diameters; or with 2 oz. cases, first filled one diameter with gold fire, then one and one-fourth diameters of brilliant fire. These cases must be well secured at top of the charge, lest they should take fire at both ends: but their necks must be larger than the common proportion. For the manner of forming _balloon cases_ of paper, consult the article on that subject, in a preceding chapter.

Balloons, the _bombs_ of some, may be formed of different sizes, and made proportionably strong.

Bombs may be formed of wood by turning it round, and hollow, of a sufficient thickness, and in two parts, which fit each other like a common snuff box. The inferior or lower part must be made thicker than the upper, as it rests upon the powder; and for the same reason, that iron bombs are cast thicker at their bottom. One-twelfth of the diameter is considered a sufficient thickness for the under part, and one-fifteenth for the upper part, which is pierced with a hole to receive the fuse. This hole is called the eye of the bomb.

When balloons, or bombs, are to be charged, the decorations may be varied in the same manner as for sky-rockets. Stars, golden rain, and meteors, are considered the best, as they produce the most brilliant effect.

After the addition of the furniture or decorations, we finish the charge by putting in coarse grain powder, which is introduced through the eye. The fuse is then driven in. It is glued, in order to secure it. The bomb is now covered with three or four turns of canvass, and over this some paper, to secure it. In this state, it ought not to be more than 1/11th of an inch smaller than the caliber of the mortar. This leaves what is denominated the windage.

When the bombs are well dried, the fuse is primed with a double match, and priming paste. A cup, made with two turns of paper, is then attached to the fuse, which receives the double match.

The bomb, thus prepared, is then placed in a cone made of pasteboard, which contains the powder of the charge, or that required for its ascension, and is put into the mortar. One of the matches above described, communicates the fire to the fuse, and the other at the same time to the powder in the cone. The match, it is to be observed, comes out of the mouth of the mortar, and serves to fire it. This mode of discharging the mortar, differs from the one we have previously given.

The following table exhibits the calibers for bombs, the length of the fuse for each caliber, and the weight of the powder required for the charge.

Having made some remarks respecting bombs, we will now offer a few observations concerning mortars; and although we have, on a former occasion, mentioned something respecting them, yet we deem a few remarks on this head not improper at this time.

_Mortars_, from five to six inches bore, are usually made of pasteboard and canvass. The canvass is first soaked in a gelato-amylaceous paste, or paste composed of half glue and half flour; and, when put on, is covered with sheets of pasteboard, which are glued or pasted. For various kinds of paste, see _Pasteboard_.

When the case, or mortar is to be formed, cylinders of wood as _formers_ are employed. They are of different diameters, according to the size of the mortars, that are to be made. For four-inch mortars, inch formers; for six-inch, one and a half inch formers, &c. After they are rolled and pasted on the former, they are dried on it. As to their strength, this depends on the thickness of the case. A mortar of four inches in interior diameter, ought to be six inches in exterior diameter, and those of six in interior, should be nine, exterior. The cases being formed, we next have turned as many cylinders of walnut, as cases or pots. These cylinders are short. In each is formed a conical chamber, in the shape of the letter V, which is afterwards lined with tin or brass, to prevent the action of the powder. They are then glued and put into the end of each pot, about the length of an inch, and further secured by nails.

The chamber is designed to receive the powder, and its conical form enables it to act with all its force immediately on the bomb. A flat bottom would not have this advantage, as the powder in that case would have more room, and consequently its force be divided. They are sometimes, however, made flat.

The charge for these mortars, as a general rule, is 1/30th part of the weight of the bomb.

When mortars are to be larger than the sizes we have mentioned, it is necessary to have them of metal, and for this purpose copper is generally employed. Its thickness should be one-fourth of an inch, for a nine-inch mortar; and half an inch, for twelve-inch mortars. A cone of copper is to be made in the same way as above mentioned. This is secured, and made solid by means of lead.

In experiments and exhibitions, the powder, we may observe, must be of the same strength.

We find then, that mortars, for the discharge of bombs, or balloons, are differently made from those which are used for throwing iron-shells. In fire-works, the design of mortars is to project the balloon in a vertical direction, which, being furnished with a fuse as in ordinary shells, receives the fire from the gun-powder; and at a given time, according to the length of the fuse, the fire is communicated to the balloon, which bursts and scatters its contents in the atmosphere. The furniture for balloons being various, and in a larger quantity than could be contained in the heads of rockets, (except the Congreve,) the appearance is more grand and impressive. It is obvious, that, when they burst, fire is communicated to the whole at the same time; and the quantity of powder is usually sufficient, not only to burst the shell, but also to throw the contents to some distance. The height, to which balloons ascend, depends, of course, on the quantity of gunpowder put in the mortar. The quantity is generally regulated.

We find, also, that two modes are used for discharging the mortars. The one consists in having a communication from without to the bottom of the cone, which contains the powder, and applying the match to this vent, on the same principle as that for firing a cannon, or common mortar. The other, by firing a quick-match in the conical cavity, and putting in the charge with the balloon; letting the match, however, be of a sufficient length to come out of the mouth of the mortar, and fall over its side. This match, when fired, will communicate fire to the powder in the cone, and produce the same effect. Metallic cylinders, and especially copper, however small, are certainly preferable to those made in the usual manner.

_Sec. IV. Of making Balloon Fuses._

Wood, particularly beech, is generally employed for forming fuses, which is turned of the shape required. If made with pasted paper, they will answer for the purpose of fire-works. The diameter of the former for fuses for coehorn balloons must be half an inch; for a republican fuse, five-eighths of an inch; for an eight-inch fuse, three-fourths of an inch; and for a ten inch fuse, seven-eighths of an inch. Having rolled the cases, pinch and tie them almost close at one end; then drive them down, and let them dry. Before they are filled, mark on the outside of the case, the length of the charge required, allowing for the thickness of the bottom; and when the composition is rammed in, take two pieces of quick-match about six inches long, and lay one end of each on the charge, and then a little meal-powder, which is to be rammed down loose. The loose ends of the match, double up, and place in the top of the fuse. This top must be covered with a proper cap to keep it dry. When the shells are put into the mortars, uncap the fuses, and pull out the loose ends of the match, and let them hang on the sides of the balloon. The use of the match is to receive the fire from the powder in the chamber of the mortar, in order to light the fuse. When the shell is put in the mortar, its fuse must be uppermost, and exactly in the centre. Some meal-powder is usually sprinkled upon it.

Fuses of wood are longer than those of paper, and not bored through, but left solid about 1/2 an inch at bottom; so that, when used, this end is cut off. They are sawed, however, at a proper length, measuring the charge from the cup at top. On the subject of _Fuses_, see the last part of the work.

Fuses for bombs, Morel remarks, are formed of five thicknesses of paper, or of pasteboard, made of that thickness; and the former, on which the fuse case is rolled, should be one-third diameter. The composition is put in with a spoon, and each charge is driven with twenty strokes of a moderate size mallet.

_Composition for the fuses of bombs or balloons._

1. Meal powder, 12 oz. Sulphur, 4 -- Charcoal, 6 --

2. Saltpetre, 1 lb. 10 -- Sulphur, 8 -- Meal powder, 1 lb. 6 --

3. Saltpetre, 1 lb. 8 -- Sulphur, 8 -- Meal powder, 1 lb. 8 --

_Sec. V. Of the Mosaic and Common Tourbillon._

The _tourbillon de feu_ of the French, or whirlwind of fire, is the same as the _soleil montant_; because it ascends in full illumination, and scatters fire in various directions. The tourbillon, therefore, receives its name from the effect it produces. It raises itself very high, and forms a whirl of fire and terminates in two coronal figures, or crowns, which descend in what are called parasols. It does not, however, produce crowns, except when it is charged with Chinese fire.

There are two kinds of tourbillons, which we will describe, namely, the mosaic and the common. The mosaic produces a tail of some length, and after whirling round, finishes with a report. This effect is owing to its particular structure and formation, as it differs from the common tourbillon. In preparing the cases for mosaic tourbillons, pasteboard, formed of five sheets of paper, is used. They are made seven inches in length upon a roller or former 5/12ths of an inch in diameter. Their thickness, when rolled, is 1/8th of an inch. They are choaked in the usual manner, and the excess of the string is cut off. After having put a quarter of an inch of earth into a case, and beating it with ten or twelve blows with the mallet, we mark the height of the earth on the outside of the case. We then load it to the height of 7/12ths with the composition heretofore mentioned. Another quarter of a spoonful of earth is then put in. We then choak, and bind the case in this place. Two fingers of grain powder are now added; we again choak, and bind it above this. We put in the same composition, after the last operation, to the height of 7/12ths of an inch. The choaking, it is to be observed, must not wholly close the case; so that the composition can set fire to the powder.

We now introduce a spoonful of earth, and choak and bind as before. It is then finished by charging it with 7/12ths of an inch of composition. The remainder of the case is cut, and the composition primed.

Cases, thus prepared, are afterwards treated in the following manner: We pierce three holes in the sides of each, one a little above the last choak, another through, or into the case, to penetrate the last charge, and the third through the first charge. These holes have a communication with each other by means of quickmatch; so that, when the match is set on fire, the two extremes are inflamed at the same time, and being opposed to each other, give a rotary motion to the tourbillon, which, when the powder inflames, terminates by an explosion. The holes ought to be covered with three or four turns of pasted paper. It is then ready to be put into the _pots de chasse_. When completed, the tourbillon should not exceed 10/12ths of an inch in diameter.

The _pots de chasse_ (mortars somewhat similar to those described) should be made of pasteboard, prepared with eight thicknesses of paper, and moulded upon a roller of 11/12ths of an inch in diameter. They are mounted in the same manner as _fire-pots_, and are also primed in the same way.

Into each pot there is put four drachms of broken grain powder, and a slip of pasteboard, pierced with five or six holes, which is introduced by means of a stick. A little meal-powder is then put into the pot, and afterwards the tourbillon, the primed end of which must be above the _chasse_. It is then closed with paper, made into a wad or ball, and the pot is secured with a slip of pasteboard, pasted on it.

_Composition of Mosaic Tourbillons._

1. Meal powder, 16 oz. Charcoal, 3 or 4 dr.

2. Meal powder, 16 parts. Charcoal, 3⅓ ----

Common tourbillons differ in many respects from the mosaic, although their motion is the same. There are two methods of forming them as well as their appendages, both of which we purpose to describe. The first is the following: Having filled some cases within about 1-1/2 diameters, drive in a handful of clay, prepared, of course, in the manner described in the first part of the work; then pinch their ends close, and drive them down with a mallet. Then find the centre of gravity of each case; where you nail and tie a stick, which should be 1/2 an inch broad at the middle, and run a little narrower to the ends; these sticks must have their ends turned upwards, so that the cases may turn horizontally on their centres. At the opposite sides of the cases, at each end, bore a hole close to the clay, with a gimblet the size of the neck of a common case of the same nature. From these holes, draw a line round the case, and, at the under part of the case, bore a hole with the same gimblet, within half a diameter of each line, towards the centre; then from one hole to the other, draw a right line. This line divide into three equal parts, and bore a hole near to each of the ends; then from these holes to the other two, lead a quick-match, over which paste a thin paper.

It is to be observed, that there is a stick about the length of the case, which goes across it, and is securely fastened by a cord, that the whole lies flat upon a table before it is fired, and hence, it is sometimes named the _table tourbillon_; and, that the leader should be carried from one side hole to the other, the holes being made at the opposite sides, as before mentioned. When tourbillons are fired, they must lay upon a smooth table, with their sticks downwards, the leader being set on fire in the middle with a port fire. They should spin two, three, or four seconds round the table, before they rise, which is about the time the composition will be burning from the side holes to those at the bottom.

Reports, or detonating cases, may be fixed to tourbillons, if so required. In this case, we make a small hole in the centre of the case at top, and in the middle of the report make another. Then place them together, and tie on the report, and, with a single paper, secure it from fire. By this method, small cases of stars, rains, &c. may be fixed on tourbillons, being careful, nevertheless, that they are not overloaded.

One-eighth will be a sufficient thickness for the sticks, and their length equal to that of the cases.

The other mode of forming common tourbillons, is the following: They are made with cases of an inch, which are choaked and bound in the usual manner. In filling, we make two wads of paper of the same size, and put one of them into the case, and ram it with fifteen or twenty blows. We then mark upon the case, the height of this wad, which is afterwards driven with the composition, given at the end of this section. To each charge, thirty strokes of a moderate size mallet, will be required; and each charge should not be more in height in the case than nine exterior diameters. We mark, on the outside of the case, the height of this charge, and put in a wad of the same kind and size as the former one. We drive this in the same manner as the first, and then choak and bind the case. After cutting off the excess of the ligature, with which we bound the case, we again introduce the rammer, and give it eighteen blows with the mallet, in order to flatten the choak.

We afterwards divide the case parallel to each end, into four equal parts, and mark the height of the wads. That of the middle, which becomes in fact the bottom of the case, (from the manner it is fixed for ascension), we divide into five equal parts from one point to the other, and pierce a hole in each division to the composition. We then make, on a level with the wads, upon the lateral lines, two similar holes; one upon one side, and the other on the other side, at the opposite ends. These holes are so made as that the case has four holes on one line, and one upon each of the other two. Each hole is then primed with a piece of quick match, and priming paste. One of these matches must pass over all the other holes; so that the fire may be communicated from one to the other at the same time. The matches are then covered with a band of pasted paper. To hold the tourbillon in a horizontal position, we procure a hoop of the same thickness and diameter as the length of the case; and on the plate, we make a groove for the match of communication, which is supported between the four holes with an iron wire. If the case whirls round with a uniform motion, it is well balanced.

The four holes beneath, serve to raise it in the air, and the two lateral apertures give it a revolving motion.

When tourbillons are to be set off, they must be balanced either by a cross stick, as in the first instance, or some other contrivance. The effect is the same as before described.

_Composition for Tourbillons, or Table Fusées, of different Calibers._

-------------+----------------+-------------------+------------------ Substances. |Calibers of ⅓d |Of ⅔ds of an inch |Of ⅚ths of an inch | of an inch. |with Chinese fire. | with Chinese fire. -------------+----------------+-------------------+------------------ Saltpetre, | 8 oz. | 16 oz. | 16 oz. Sulphur, | 4 oz. | 8 oz. | 8 oz. Meal-powder, | 16 oz. | 18 oz. | 16 oz. Charcoal, | 1 oz. | | Pulverized | | | cast iron, | | 10 oz. | 12 oz.

_Another composition for a caliber of half an inch, of common fire._

Saltpetre, 16 oz. Sulphur, 4 -- Meal-powder, 7 -- Charcoal, 4 --

The following formulæ are sometimes used;

_For four-ounce tourbillons._

Meal-powder, 2 lbs. 4 oz. Charcoal, -- 4½ --

_For eight-ounce tourbillons._

Meal powder, 2 lbs. Charcoal, 4¾ oz.

_For large tourbillons._

Meal-powder, 2 lbs. Saltpetre, 1 do. Sulphur, 8 oz. Beat-iron, 8 oz.

As a general rule, we may remark, that the larger tourbillons are made, employing, if necessary, different coloured fires, the weaker must be the charge; and, on the contrary, the smaller, the stronger their charge.

_Sec. VI. Of Mortars for throwing Aigrettes, and the manner of loading and firing them._

Pots of aigrette, when inflamed, exhibit the appearance of an aigrette, or cluster of rays, such as are produced by diamonds, when they are arranged in a particular way. The aigrette takes its name from a bird, whose feathers serve to make up an ornament for the head. It was given in diamonds, as a particular mark of distinction, by the Grand Signior, to Lord Nelson, after the battle of the Nile. There are aigrettes made of glass.

For the purpose of throwing aigrettes, the mortars are generally made of pasteboard, of the same thickness as balloon mortars, and two and a half diameters long in the inside from the top of the foot. The latter must be made of elm without a chamber, but flat at top, in the same proportion as those for balloon mortars. These mortars must be bound round with a cord as before mentioned. Sometimes eight or nine of these mortars, of about three or four inches in diameter, are bound altogether, so as to appear as one; but when they are prepared for this purpose, the bottom of the foot must be of the same diameter as the mortars, and only one-half a diameter high. Having bound the mortars together, fix them on a heavy solid block of wood. To load them, place over the inside bottom of each, a piece of paper, and spread on it one and a half ounces of meal and grain powder mixed; then tie the serpents up in parcels with quickmatch, and put them in with their mouths downwards. Care must be taken, that the parcels do not fit too tight in the mortars, and that all the serpents have been well primed, or wetted with the paste of meal powder and spirit of wine.

On the top of the serpents, in each mortar, lay some paper or tow; then carry a leader from one mortar to the other, and from all the outside mortars to that in the middle. These leaders are to be put between the cases and the sides of the mortar, down to the powder at bottom. In the centre of the middle mortar, fix a fire pump, or brilliant fountain, and sufficiently long to project out of the mouth of the mortar. Then secure the mortars, by pasting paper over their tops.

The _nest of serpents_ (as mortars thus prepared are called) is fired by lighting the fire-pump, which, when consumed, will communicate to all the mortars at once by means of the leaders.

Single mortars are called _pots des aigrettes_. If the mortars, when loaded, are sent to any distance, or liable to be much moved, the firing powder should be secured from getting amongst the serpents, which would endanger the mortars, as well as injure their performance. To prevent this accident, the mortars are to be loaded in the following manner; First, put in the firing powder, and spread it equally; then cut a round piece of blue touch paper, equal to the exterior diameter of the mortar, and draw a circle on it equal to its interior diameter, and notch it as far as that circle: then paste that part, which is notched, and put it in the mortar close to the powder, and stick the pasted edge to the mortar. This will secure the powder at the bottom, so that it may be moved and carried without receiving any damage.

For mortars of six, eight, or ten inches diameter, the serpents should be made in one and two-ounce cases, six or seven inches long, and fired by a leader, brought out of the mouth of the mortar, and turned down the outside; its end being covered with paper, to prevent the sparks of the other works from setting it on fire. For a six-inch mortar, let the quantity of powder for firing be two ounces; for an eight-inch, two ounces and three-quarters; and for a ten-inch, three ounces and three-quarters. Care must be taken in these, as well as small mortars, not to put the serpents in tight, for fear of bursting the mortars. These mortars may be loaded with stars, crackers, &c.

_Sec. VII. Of Making, Loading, and Firing Pots des Brins._

These are formed of pasteboard, and must be rolled pretty thick. They are usually made three or four inches in diameter, and four diameters long; and pinched at one end like common cases. A number of these are placed on a plank in the following manner: Having fixed on a plank two rows of wooden pegs, cut, in the bottom of the plank, a groove the whole length, under each row of pegs. Then through the centre of each peg, bore a hole down to the groove at bottom, and, on every peg, fix and glue a pot, whose mouth must fit tight on the peg. Through all the holes, run a quick-match, one end of which must go into the pot, and the other into the groove, having a match laid in the groove from end to end, and covered with paper; so that, when lighted at one end, it may discharge the whole almost at the same instant. In all the pots, put about one ounce of meal and grained powder. Then in some put stars, and in others rains, snakes, serpents, crackers, &c. When they are all loaded, paste paper over their mouths. Two or three hundred of these pots being fired together, make a brilliant appearance by affording so great a variety of fires.

_Sec. VIII. Remarks respecting Fire Pots._

Fire pots, called also _pots of ordnance_, in pyrotechny, are nothing more than vessels used in, as well as for, the exhibition of artificial fire-works. They are generally formed of thick pasteboard, made by pasting together six or eight sheets of paper, of two inches interior diameter, three inches exterior diameter, and fifteen inches long. They are always placed upon a solid block or plank, and preserved in a firm position. There is a stopper or plug made of wood, which goes one inch into each case or pot, and is there glued and secured by nails. This plug is turned with a screw, which enters the plank, and preserves the pot in a steady position. The plank, on which the pots rest, is usually three inches wide, an inch and a half thick, and sufficiently long to receive twelve pots, placed at the distance of half an inch apart. Before the pots are fixed on, a hole is made through each plug in its centre, to receive a quick match, which passes through to the composition. A groove is also made in the plank, in its length, one-third of an inch square; and in such a manner, that the holes, which communicate to the interior of the pots through the plugs, must come in the middle of the groove. When the quick-match is put through the plugs, to communicate with the interior of the pots, we must leave about two inches on the outside. At each hole, also, we put some priming paste, and then permit it to dry.

If it is required to discharge them all at once, this may be done by making a communication through the groove, by means of leaders in the manner before mentioned; and covering the leaders with four or five bands of paper, and setting the match or leader on fire. If, on the contrary, they are to go off in succession, the groove is filled with bran, which is pressed with the fingers, and is then covered with paper. The match of communication with the pots must, however, be preserved. The bran causes the fire to communicate gradually from one to the other.

Pots are charged in the following manner: We first make the _sacs of powder_. For this purpose, we have as many squares of paper as there are pots, which are made into cylinders on the same roller that formed the pots. Into each is put about an ounce of the charge-composition, hereafter mentioned, with two pieces of match, sufficiently long to come out an inch. They are then closed and tied, and the excess is cut off. One of these sacs is put into each pot, having previously pierced it with several small holes, and sprinkled it with meal powder. After this, the garnishing, furniture, or decoration is added, always observing to put the primed part downwards. A wad of paper is then put over the whole, and the mouth is closed with pasted paper.

_Composition of the charge for fire pots._

Gunpowder, in broken grains, 16 oz. Charcoal, 3 --

Fire pots are discharged in the way we have described, which is considered the best and most certain; or they may be fired by communicating the fire with a match, passing out of the mouth, and hanging over the sides. Another mode may be used, similar to that for discharging balloons or bombs, but on a scale proportionate thereto. Pots may be discharged in any direction; hence two pieces, or sets, may be fired adversely, like rockets from the regulated rocket case. Their effect depends, as we have frequently observed, on their furniture or decorations.

The strength of fire pots is also to be considered. If they are made three inches in interior diameter, it is prudent to cover them with stout canvass, or small cord, wrapped round and covered with a coat of glue, in the same manner as for tourbillons.

Fire pots are calculated to throw serpents, &c. in the air. Mortars, it will be recollected, are designed to discharge shells or balloons, which are thrown to a considerable height, by the powder placed in the conical cavity; whereas fire pots, although their contents are thrown out by blowing powder, are differently made at the bottom, and merely designed to project serpents, stars, &c. to a small distance. Being primed, they take fire as they pass out of the pot. The charge is sometimes gunpowder, and, as above, composed of gunpowder and charcoal, to lessen the power of the former. The principle, on which they are discharged, is the same. Fire pots are called pots of ordnance, because they are used for discharging sundry substances, by means of gunpowder.