An oval stone, with what appears to be a cup-shaped depression on one face, 3∕8 inch deep, is engraved by Schoolcraft[909] as a relic of the Congarees. Another, from the Delaware River, of the Danish form, is described by Nilsson[910] as a tool for making arrow-points. He also engraves one from Greenland. Other so-called hammer-stones in the same plate are more probably “strike-a-light” stones, and under any circumstances belong to the Early Iron Period. Abbott[911] and Rau[912] also describe Indian hammer-stones, some like Fig. 161. Highly polished, and deep cup-shaped or conical depressions are occasionally to be observed occurring on one or both faces of large pebbles, usually of quartz, and sometimes in two or three places on |242| the same face. Though very similar to the hollows on the hammer-stones, they are due to a very different cause, being merely the results of stone bearings or journals having been employed, instead of those of brass, for the upright spindles of corn mills. It seems strange that for such a purpose stone should have gone out of use, it being retained, and indeed regarded as almost indispensable for durability, in the case of watches, the pivot-holes of which are so frequently “jewelled.” [Illustration: Fig. 162.—St. Botolph’s Priory. 1∕2] Fig. 162, which I have reproduced from the Sussex Archæological Collections[913] on the same scale as the other figures, shows a pivot-stone of quartzite (?) found in the ruins of St. Botolph’s Priory, Pembrokeshire, a few yards from a pebble (4 1∕2 inches) of similar material, in which a hole had been bored to the depth of half an inch apparently by the friction of the pointed end of the smaller pebble. Another pivot-stone of the same kind was found at Bochym,[914] Cornwall. Such socket-stones were, until recently, in use in Scotland[915] and Piedmont[916] for the iron spindles of the upper mill-stones of small water-mills. Pivot-stones with larger socket-stones were also used for field-gates. Similar socket-stones occur in Switzerland,[917] and have puzzled Dr. Keller. A stone, with a well-polished cavity, found on the site of an old mill near Carluke, Lanarkshire,[918] was exhibited at Edinburgh in 1856. Another was found in Argyllshire; and I have seen other specimens from Ireland. The socket of the hinge of the great gate at Dunnottar Castle is said to have consisted of a similar stone. Stones with highly-polished hollows in them, in which apparently the ends of drill-sticks revolved, are common on the site of ancient Naukratis.[919] [Illustration: Fig. 163.—Bridlington. 1∕2]