6. Pyramid of Flower Pots.
In general construction, this article is exactly similar to the one just described; but in place of gerbes, or fire-pumps, it is loaded with mortars, filled with Serpents, Crackers, &c. and having in the centre of each a case filled with spur-fire. The mortars should be made of paste-board, wound two or three times round a cylinder, about four inches diameter, and well secured by glue, by which means their bottoms and tops are fixed to them.
The spur-fire, which is the chief ornament of these pieces, is prepared as follows:—It has been said that excellence can never be obtained, without overcoming commensurate difficulties; this is certainly verified in the preparation of this composition; for nothing can exceed the difficulty and trouble in preparing it, and nothing can exceed the beauty of its appearance when properly prepared. It is said to be the invention of the Chinese, and is certainly the most beautiful and curious of any yet known.
The principal care in the preparation, is, to have the ingredients of the very best quality; next to that is the well grinding and mixing them together.
The proportion of the ingredients is salt-petre four pounds and a-half, sulphur two pounds, and lamp-black one pound eight ounces. One great difficulty is in the mixing these ingredients together; it is best to sift the salt-petre and sulphur together first, and then put them into a marble mortar, and the lamp-black with them, which must be worked down by degrees with a wooden pestle, till all the ingredients appear of one colour, which will be somewhat grayish, but more inclined to black; when this is done drive a little into a case for trial, and fire it in a dark place; if sparks come out in the form of stars or pinks, and in clusters, spreading well without any other sparks, it may be considered good: if it appear drossy, and the stars not full, it is not mixed enough; but if the pinks are very small, and soon break, it is indicative of an excess of rubbing; if the excess is great, it will be too fierce, and hardly show any stars: on the other hand, if the rubbing or mixture is in defect, it will be too weak, and produce nothing but an obscure or black smoke.
This composition is generally rammed in one or two ounce cases, about five or six inches long; care must be taken not to ram it too hard. The aperture at the choak should not be so wide as is usually given to other choaked cases.
It is somewhat remarkable, that the composition should be improved by being kept in the cases; but it is found that they always play better, if suffered to stand a time after they are filled.
In preparing the Pyramid of Flower Pots, the cases of spur-fire are to be placed in the middle of the mortars, and be connected by leaders, so that they may all be fired together. The cases will first play off in a very pretty manner; and when exhausted, the fire from them communicates to the powder at the bottom of the mortars, and this suddenly taking fire, all blow up simultaneously, and scatter their luminous fragments in the air; the serpents hiss, the crackers bounce, and the illuminated stars fly in all directions, producing considerable amusement and surprise, and forming an excellent conclusion to a small exhibition.
This beautiful composition is also susceptible of other representations, many of which may without the least danger be exhibited within a room, as well as in the open air; it is really of so innocent a nature, that it may be (though improperly) called a cold fire; for it is found that when well made, the sparks will not burn a handkerchief when held in the midst of them; they may be held in the hand with perfect safety; if the sparks fall a short distance upon the hand, you feel them like drops of rain.
A pretty exhibition may be produced by placing a number of spur-fires round a transparent pyramid of paper, and fired in a room, or in the open air. In all cases, and every variety of exhibition, this fire is very beautiful, and will always repay the labour of preparation.