An empty case, which has not been choked, is fastened on one of these rockets and is then threaded on a taut cord. When the rocket is set on fire, it moves rapidly from one end of the cord to the other.
If a jet, charged with the composition for turning suns, is fastened on this rocket so as to form a cross, then, when both pieces are set off at the same time by a communicating match, the rocket, in addition to its flight forward and backward, will also revolve in the manner of a sun. (PL VI, fig. 5. )
Rockets having a double movement are made by attaching two rockets one to the other in such wise that the massif of one rests against the throat of the other. Or they may be placed end to end, massif against massif, with a single match to communicate the fire. The match is inclosed in a lance case, which is firmly fastened to both rockets by pasting paper over it. An empty case is then attached to the pair of rockets, and is threaded on the cord. (PL VI, figs. 7 and 9.)