The chromatrope has been developed and enlarged until for important display work quite elaborate pieces are fired under this name. Lancework of geometric form is used on the bars or spokes, and the intersection of these, forming ever-changing geometrical designs, adds greatly to the effect of the intersection of the fire. This effect is the basis of the Guilloché, a somewhat elaborate piece which falls in Ruggieri’s third class. It consisted of six wheels placed one behind the other in pairs of graduated size; the two smallest—which fired first—had six cases, the next eight, and the largest forty-eight, and was twenty feet in diameter. The next described is the Salamandre, a piece which, on a large scale, is still occasionally fired at the Crystal Palace. It shows a snake in pursuit of a butterfly which it seems to overtake but never quite catches. The mechanism is an endless chain of wooden links running in and out between eight sprocket wheels, arranged in octagon formation. About half the length of the chain is made out and lanced to represent the snake, and a lancework butterfly is situated in the centre of the other half. Ruggieri claims that his father fired this piece and the guilloché in 1739 at Versailles. The other pieces mentioned in this section are too elaborate for description in the space available, but are interesting as showing the use of the helix and spiral as applied to wheels and cones, as secondary elements of larger pieces. The modern designer of pyrotechnic pieces has great advantage over the earlier practitioners in that he has available an infinitely larger range of colour and other composition. It is often possible to get a much-enhanced result with less cases giving more or varied effects as opposed to a larger number of cases of similar effects, which, in an attempt to produce a lavish show of fire, end in confusion. His fourth division begins with the “Caprice simple”; this is the modern horizontal wheel. This wheel is similar in arrangement to the vertical above-mentioned, except that its cases are arranged so that the first plays horizontally in the plane of the wheel, the next at an angle downwards, and the third upwards. This succession is repeated with the remaining three cases. In addition, the horizontal wheel has either a mine which is lit from the last case, or Roman candles and mine, at the centre playing upwards. The second form is arranged so that the Romans are fired simultaneously with the fourth case and the mine from the last.