Nomenclature of Ordnance

—For component parts of cannon and their description, see Cascabel , Base of the Breech , Base-line , Base-ring , Breech , Chase , Astragal and Fillets , Neck , Swell of the Muzzle , Face , Trunnions , Rimbases , Bore , and Reinforce . For recent modifications in the external form of cannon, see Ordnance, Strains upon . United States. — Smooth-bored. —The official system for the land service comprises the following smooth-bored cannon: The Napoleon gun for field service (see Napoleon Gun ) and the mountain howitzer for mountain and prairie service. (See Howitzer .) For siege purposes, the 8-inch howitzer, 8- and 10-inch and 24-pounder Coehorn mortars,—and for sea-coast defense, 13-, 15-, and 20-inch (Rodman) and 10-, 13- and 15-inch mortars. No 15-inch mortars have been yet cast. The 24-pounder flank defense howitzer, as well as the 8- and 10-inch smooth-bored Rodman and the 10-inch sea-coast mortar, no longer belong to the system, and are no more to be cast. The 13-inch smooth-bore is an experimental gun, not more than two or three of which have been cast. The smooth-bored gun principally used in the naval service is the Dahlgren. (See Ordnance, Construction of .) The carronade is now little employed.