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 the rocket with a clay diaphragm evidently suggested that the choking of the case might be dispensed with where the composition was less fierce, the necessary reduction of the orifice being produced by a clay diaphragm with a central hole of sufficient size. This method is followed with the gerb, fountains, and flower pot, and in the firework known to pyrotechnists as “fixt”; this unit is largely used in display work to form the fringe frame or lattice effect of a set piece. “Fixt” are made in 1 oz. and 2 oz. sizes, and contain a composition of approximately one part of steel filings to four of mealed gunpowder and finish with a bounce. The origin of the name is uncertain: it may refer to their use on fixed pieces in contradistinction to one revolving, or—as is most probable—was first used to distinguish between a fixed and a moving rocket. The time of the introduction of the clay choke is uncertain. Jones, writing in 1765, although using clay in the heading of rockets, still choked all cases, but Mortimer (1824) uses it, although Ruggieri (1821), whilst doing the same, appears to think choking preferable. The former gives instructions for charging the clay solid and boring the central hole; Ruggieri, however, uses a nipple like a much shortened rocket spindle, in which he agrees with the modern practice. This method is also utilised at the present time for small-sized rockets.