Excerpt from Abrasives and Abrasive Wheels, Their Nature, Manufacture and Use: A Complete Treatise on the Manufacture and Practical Use of Abrasives, Abrasive Wheels and Grinding Operations The art of finishing metals by abrasion is one of the oldest mechanical practices in existence, dating from the time prehistoric man discovered that he could fashion his wood and bone implements by rubbing them on rocks of a gritty nature. The grindstone is, without doubt, the oldest form of grinding wheel known. With the early development of the mechanical arts, it was discovered that a sandstone cut in circular shape and mounted upon a revolving shaft, showed higher efficiency than the side of a rock for sharpen ing and shaping various implements. It is definitely known that grindstones, rotated by power, were used in the manu facture of armor as early as the year 1570. It is also known that the emery deposits of the Grecian Archipelago were known to the ancients and the value of this abrasive recognized, as many writers of early days referred to emery under various names. In considering some of the mechan ical achievements of the handicraftsmen who worked with metals centuries before the Christian era, it is hard to conceive how they attained so high a degree of perfection without the use of an alumina abrasive for tool-sharpening purposes. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.