The genouilleres are for display on water - the equivalents of serpents for display in the air. They are used to garnish fire pots, water balloons, and barrils de trompes. They are also called dolphins and ducks. Their effect is to rise from the surface of the water, to throw themselves repeatedly into the air, and to finish with an explosion. The cases have a length of nine interior diameters, without including the throat. They are loaded upon a base holding a spindle, which has a thickness of one-quarter of the interior diameter. After three charges of the composition, a half-charge of powder is added; and this method is continued with each three charges, until the height of the seventh diameter is reached, when a wadding is driven down on the composition. This is pierced with an awl, which just reaches to the composition. A pinch of powder is placed in the hole, and grain powder is then used to fill the remaining space, reserving only room for a final wadding, with which the powder is covered, and for the choking.
The sheath is next attached to the same end of the loaded case. This sheath is an empty case, very thin, of the same size as the other, and closed at one end, either by choking or by a pasteboard disk pasted over it. It is cut at the other end into several little tongues. The loaded case is pushed within this cut portion, which serves for bending the sheath. This bend should form an angle of about 50 degrees. Heavy thread is tied over it, and a band of paper is pasted over the string. The sheath, apart from the tied portion, should have a length half that of the case. The piece is then choked and primed as are jets. (PI. VIII, fig. 4.)
All aquatic pieces for use should be rubbed with tallow to prevent water from penetrating. The tallow is melted, and with a large brush of hog's bristles is spread over the entire surface of the genouilleres. They are then ready to be employed as garnitures, or to be fired directly by hand.
The sheath should sustain on the surface of the water that part to which it is attached. As to the throat, this is sustained by the empty space created by the burning of the material. The elbow joint of the sheath gives the genouilleres an uneven and tortuous movement, while the powder, of which one-half a charge is added after three charges of the composition, causes them to leap into the air when the fire reaches it.