Definition
A tourbillion is a small self-propelled tube whose burning composition escapes through side vents and spins it on its axis as it rises, drawing a spiral of sparks often accompanied by a whistle. The serpent is its erratic cousin: a thin, unstabilised tube that zigzags at random leaving a trail. Both are found in cakes of 20 to 30 mm, in shells of 75 to 150 mm that release them in a swarm at the apex, and in mines that throw them from the ground. They rise 10 to 40 m and last one to three seconds each, but a swarm of fifty creates a much-loved living cloud. In English the spiral is a tourbillion while the erratic variants are called serpents, hummers or fish, the latter being the “fish” that swim across the sky.
In practice, for the display company
Tourbillions and serpents sometimes land still burning and unpredictably: on a narrow site they are fired well away from the audience and never in strong wind. PyroDesk records them with their effect type and duration, and PyroSimulator animates the spirals and zigzags, swimming fish included, so the swarm can be judged within the sequence.