A good bottom may be formed by chalk rammed down close.
Such stones may be of any size subject to each of them covering only a small proportion of the width of the structure (in the Vyrnwy dam they reached 8 or 10 tons each), and the spaces between them, where large enough, must be similarly built in with smaller, but always the largest possible, stones; spaces too small for this treatment must be filled and rammed with concrete.
This mixture may be rammed in place, or baked blocks of it may be laid up like a masonry wall.
A sheet iron case is then placed within the furnace, and the space between it and the walls rammed with limed charcoal; the interior is filled with fragments of the iron or copper to be alloyed, mixed with alumina and coarse charcoal, broken pieces of carbon being placed in position to connect the electrodes.
A naval battle was fought on the 5th of May 1864, in which the double-ender "Sassacus" most gallantly rammed the "Albemarle" and was disabled alongside her, and Smith's vessel and others, unarmoured as they were, fought the ram at close quarters.