French Commissioner & Gunners c.1672
Each Piece in a battery must have its Commissioner or Master Gunner and its Gunners.
A commissioner must be bold, skilful and experienced, because it is he who must point the piece by means of the visor and the quills, which he raises or lowers as he sees fit, according to his knowledge of the scope of the pieces and their calibre. While a barrel is being fired, the steward must take care to ensure that the ball has the desired effect, so that it retains its shape or changes its pointing.
The duty of the gunner is, as soon as the piece has fired, to refresh it with the swab in vinegar or urine, and to put in it without wasting time the powder, the stuffing, and the cannonball. Two of those who serve at the barrel are careful to put the piece back into position. The commissar points it and fires it.
A gunner who knows his job well takes care not to put the powder in a piece that has just been fired, without cooling it beforehand, because of the heat that is kept for a long time in the metal.
Each piece must have its own people to serve it, its own magazine of powder and calibre balls, with a provision of care to stuff it but in a place where no spark can fly.