Page:Pyrotechnics the history and art of firework making (1922).djvu/211

 gained by experience. An amateur at a first attempt might possibly be successful in lighting all the cases on a piece, but he would be very unlikely to produce that instant and symmetrical ignition which denotes the skilled pyrotechnist.

The smaller wheels have turning cases, that is, small rockets to give them motion; these burn through very rapidly, and the continuation of movement is provided for by capping the turning cases at either end and leading them up vent to head in series; the motive power for the larger display pieces is provided by gerbs, which, from the nature of their fire, give more effect than would rocket cases, and have the further advantage of burning longer.

It would not be possible in the present work to give a complete catalogue of the varieties of pieces which have been produced, but the list given by Ruggieri is typical of the whole, and includes many of the smaller compound pieces in use to-day for shop and small display work.

The larger display pieces are generally designed and redesigned season by season by pyrotechnists, and are certainly being elaborated and improved. They, however, fall generally into certain classes in the same way as do those given by Ruggieri. His classification is as follows:

1. Stationary fireworks. 2. Fireworks turning vertically. 3. Mixed fireworks or fixed and turning. 4. Fireworks turning horizontally or on a pivot. 5. Built-up pieces turning on a pivot. 6. Cut-out pieces and transparencies.

Of these, the last mentioned class are now obsolete: they consisted of transparent and silhouette pictures or designs illuminated from behind. He also includes both simple and