This Federal accoutrement is a relic condition artillery device known as a naval watercap fuse. Of wartime design, this tapered, cylindrical-shaped brass fuse adapter is the type utilized by the US Navy in its big guns.  Made to fit many caliber shells, a special fitting lead watercap with a crooked channel was threaded into the top of the fuse to prevent the time composition flame from being snuffed out by the water.  The fuse adapter measures 1¼” diameter at the flange head, has a tapered body and is 2 3/8” long.  Device has a flat head with two notches to accommodate the fuse adapter ammo tool.  No anvil cap.  Specimen has twelve threads per inch with a wide circular opening at the lower end.  Stamped on the flange head is “ORD” (small anchor) / 1861” indicating it was produced by the US Ordnance Dept. in 1861.  Letters have eroded and are difficult to see especially the naval anchor. Copper has acquired a pleasing, greenish patina overall.