Page:Pyrotechnics the history and art of firework making (1922).djvu/176

 and the contents ignited by an opening charge of powder lighted through a hole bored in the clay diaphragm above the heading, so that when the heading is burnt through the fire may be communicated to the opening charge.

From earliest times the rocket has been the chief item in recreative fireworks; either the sky rocket as we know it today or its many modifications and derivatives was the chief constituent of the early displays.

During the sixteenth and seventeenth centuries a display would contain the following items—dragons or similar figures issuing from the scenic castle provided for the display; these would be moved by line rockets. A line rocket has no cap or garniture, the socket usually provided to hold the stick being lengthened, and of sufficient diameter to allow it to slide along a tightly stretched cord passed through it. Pieces of a similar nature to the modern fountain and gerb would be represented by "ground rockets." This is a rocket less fiercely burning, charged solid, fixed to a support so that it remains stationary whilst burning, the fire being thrown out in a jet. Rockets would also be used to turn such primitive wheels as were exhibited, and to actuate mechanical scenic devices, which are in effect the "turning cases" of the present day. Serpents of fiz-gigs were much used, both as a garniture for rockets, and to give animation to wheels and similar pieces. These were made on the rocket principle, similar to the squib, but slightly more elaborate. A choke was formed between the composition and the "bounce" or powder giving the report.

To-day the ground rocket has developed into the gerb or Chinese tree, fountains of various kinds, the flower pot—of the larger kinds; and among the smaller varieties, the squib with its variations, such as Black Jack and Blue Devil, and the golden rain with its variations.

The modern, or rather more recent, method of heading