Revelation 9:19

Their power is in their mouth - From these the destructive balls are projected; and in their tails, the breech where the charge of gunpowder is lodged.

Their tails were like unto serpents, and had heads - If cannons are intended, the description, though allegorical, is plain enough; for brass ordnance especially are frequently thus ornamented, both at their muzzles and at their breech.