A Manual of Pyrotechny; or, A Familiar System of Recreative Fire-works

by G. W. Mortimer

Small Gerbes.—These are frequently called “White Fountains;” they differ but little, when used as Gerbes, from the foregoing: they are made of four, eight, or twelve ounce cases, of any length, pasted and made very strong: before they are filled, drive in about one diameter of their orifice high some good stiff clay, and when the case is filled, bore through the centre of the clay to the composition a vent-hole of common proportion, which must be primed and capped as before.

These cases are sometimes filled with Chinese fire, in this case the clay must not be used, but filled the same as cylindrical cases, and footed and primed in the same manner.

Roman Candles.

9. Roman Candles.—Roman Candles are constructed nearly after the manner of Gerbes; their cases are made perfectly cylindrical, as above described, and between the layers of composition, are interposed balls, or stars, which are prepared as directed in Article 4. In filling and ramming Roman Candles, especial care must be taken that the stars are not broken in the operation. When the cases have been properly rolled and dried, and their bottoms firmly secured by tying them with some strong twine, it is best, previous to putting in the composition, to ram a little dry clay, which will fill up the hollow, and leave a better bottom to the case. This being properly done, put in a small quantity of corn powder, and over this a small piece of paper, just to prevent the composition from mixing with the powder; then as much of the composition is to be put in as will, when rammed hard down, fill the case about one sixth of its height; then over this a small piece of paper (covering about two thirds of the diameter) as before, then a little corn powder, and upon that a ball is to be placed, observing to let the ball be somewhat less than the diameter of the case. Over this first ball more of the composition is to be introduced, and pressed lightly down, till the case is about one third full, when it may be rammed, but with some gentle strokes, lest the ball is broken by it; then a piece of paper, a little corn powder, and upon it another ball, as before; so that the case after this manner will contain five or six balls with regular beds of composition between them, and have about the same length of composition above the highest ball. When the case is thus filled it is to be capped with touch-paper by pasting it round the orifice, and a little priming of mealed powder being added, the piece is rendered complete.

In regard to the stars or balls, it is best that their form be flat and circular, or even square rather than spherical, as they will be less liable to be injured in the filling; they should also be somewhat different in size, which is found to add much to their effect; that is, let the first star be about two thirds the diameter of the case, let the next be a little larger, and so on increasing to the fourth, fifth, or sixth, which last should fit tight into the case.

Observe also to let the quantity of powder at the bottom of each ball increase as the balls increase in diameter, or as they come nearer the top of the case; not on account of the additional weight of the ball, but, as on those balls situate near the top, the force of the powder ceases to act on the ball, sooner than on those situate lower in the case, consequently the force to throw the ball to the same distance must increase proportionally; another reason for decreasing the quantity of powder towards the bottom is, that the same quantity used with the bottom as with the top ball, would cause the case to burst, and destroy all the effect which they are intended to produce.

The composition for filling will be found in the Table, [Section 7].

The best way of exhibiting these Roman Candles is to place them in rows on a stand, some fixed quite perpendicular, others declining at different angles, that the balls may be projected to various distances, and produce a more beautiful effect. The greatest angle of declination should not exceed forty-five or fifty degrees.

A very pleasing variety of Gerbes may be produced by filling the cylindrical cases with the compositions called Chinese fire, (see next article,) being filled with red or white, and used with different proportions of the ingredients, they may be cast into many and various shades of colours.