The pot should be made of the same pasteboard as is the rocket. This is shaped on a wooden cylinder, used as a mold. The pot has a thickness of two or three turns of pasteboard according to the size of the rocket, whether large or small. (PL II, fig. 13.)
The mold of wood for shaping the board is all of one piece, but is made from two cylindrical parts of different diameters: One, on which the pot itself is rolled, has a diameter one and three-quarters times that of the rocket's exterior diameter and a length of three of these diameters. The diameter of the other cylindrical part of the mold, on which the pot is choked, is three-quarters and one-eighth of the rocket's exterior, and its length two of the same diameters.
It should be noted that with rockets of 12 lines the height of the pot should be the same as for ordinary serpents made from playing cards, so that the rocket can carry these as its garniture. As the packets of stars used for garniture have less height, the pot is accordingly reduced when they are to be used.
After the pot has been choked, that end is trimmed, leaving only sufficient length beyond the choke to permit easy tying to the rocket. This part is soaked in water to render it flexible, and after the ligature has been made, a band of blotting paper1 is pasted over it, which serves both to conceal the cord, and to prevent its loosening. (Pl. II, fig. 12.)
In garnishing the rocket, a pinch of powder is first dropped into the pot. By tapping against the case, the powder is made to enter into the holes through which fire is to be communicated to the load. A ladleful of the rocket composition is commonly called the charge. On top of it are deposited the serpents or stars that are to be cast forth. Care must be taken that these be no heavier than the body of the rocket. A rocket of 4ounces weight must not weigh more than 8 ounces after it has been garnished, and the proportion is the same as to other rockets, whether heavier or lighter. A rocket can not mount beyond a very moderate height if overloaded, but quickly returns to the earth in a curve.
The artificers describe such a firework as arched (arque), by reason of the line followed in its descent.
Waddings of torn paper are placed in the interstices about the serpent or the packet of stars, in order to prevent their shaking about, and the pot is finally closed with a round of paper pasted over it. This paper should be snipped around the edges to prevent unevenness where it is bent over the case. Pains should be taken also to dip the packets of stars into powder before placing them in the pot, in order that they may catch fire more quickly.
1 The paper thus named was of a firmer and tougher tissue than the blotting paper of to-day.
The cap is the name given to the end piece of the rocket, which has the form of a cone. It is made from a single thickness of pasteboard.
To secure the proper size, the workman traces on the pasteboard with the compass a circle of which the diameter should be one and one-third that of the pot. This round of pasteboard, when cut into halves, gives the material for forming two caps. One of these is first moistened, to take out the stiffness, and then, by turning, it is made to assume the shape of a cone with the overlapping edges pasted. (Pl. II, fig. 15.)
When the cap is dry, the edge of the circumference is cut at intervals with the scissors, in order that this part may be more readily joined over the pot to which it is to be pasted. This edge is also moistened to reduce its stiffness before pasting. The cap should be placed upright over the pot. A band of paper is pasted over the place of junction, partly to conceal it, and partly to prevent any loosening during the drying process. This band of paper should be moistened with paste on both sides. Indeed, a similar precaution should be observed in connection with any paper employed for covering the points of junction in rockets or port fires. By this means, the paper is made easier for manipulation, and the folds are less conspicuous.
The match is next attached to the rocket. A piece of fuse, folded double and of suitable length, is made to enter the hole left by the piercer, to a height, within the air chamber, of one exterior diameter. The fuse is made fast in the throat of the rocket by an application of priming paste. Care must be taken to use no more of the priming than is necessary for holding the fuse firmly. Too large a quantity would give an excess of fire, which might cause the bursting of the rocket.
A round of paper is now pasted over the throat of the rocket. This final process is called by the artificers the bonneting. The paper protection is designed to prevent the communication of fire from one rocket to another at the time of discharge. It also tends to protect the composition with which the rocket is loaded from the attacks of humidity. , Very frequently, pots are not placed on the smallest rockets. Instead, a square of gray paper is rolled and pasted on the top of the rocket, so that it projects to the height necessary for containing the garniture. The charge and garniture having been placed within this paper, the upper end is folded down over the contents, and pasted. The load of such rockets is so light that the flight is correspondingly high, but the display from the garniture is correspondingly less impressive.