Stamp Mill, Seven Troughs district, Nevada

Usual 19th-century device for crushing ore. The stamps look like big pistons, with the wide end at the bottom being the "hammer" part. The big pulley on the side turned a shaft with cams on it, which would engage pawls on the shafts of the stamps. The cam would lift the stamp and then release it as it kept turning, so that the stamp dropped onto the ore. The stamps were set up to drop successively in a particular order so as to maximize the crushing effect. (This looks like a 5-stamp unit.) As you might imagine, stamp mills made a terrific racket, especially since they were usually run 24/7. They were rendered obsolete by such things as cone crushers, which are both less prone to jamming and yield a more consistent product.