By visiting the workshops of the flint-workers, M. Dolomieu ascertained that the first shape which the workmen gave to the flint was that of a many-sided prism. In the next place, five or six blows with the hammer, which were applied in a minute, were sufficient to cleave off from the mass certain fragments as exact in shape, with faces as smooth, outlines as straight, and angles as sharp, as if the stone had been wrought by a lapidary's wheel--an operation which, in the latter case, would have required an hour's handiwork. All that was requisite, says Dolomieu, is that the stones should be fresh, and devoid of flaws or heterogeneous matter. When operating upon a good kind of flint, freshly extracted from the ground, a workman could prepare 1000 proper flakes of flint in a day, turning out 500 gun-flints, so that in three days he would perfectly finish 1000 ready for sale. In 1789, the Russian army was furnished with gun-flints from Poland. The manufactory was established at Kisniew. At this period, according to Dolomieu, 90,000 of these gun-flints were made in two months. Besides those at Grand-Pressigny, some other pre-historic workshops have been pointed out in France. We may mention those of Charente, discovered by M. de Rochebrune; also those of Poitou, and lastly, the field of Diorières, at Chauvigny (Loire-et-Cher), which appears to have been a special workshop for polishing flint instruments. There is, in fact, not far from Chauvigny, in the same department, a rock on which twenty-five furrows, similar to those in the polishing-stones, are still visible; on which account the inhabitants of the district have given it the name of the "Scored Rock." It is probable that this rock was used for polishing the instruments which were sculptured at Diorières. The same kind of open-air workshops for the working of flints have also been discovered in Belgium. The environs of Mons are specially remarkable in this respect. At Spiennes, particularly, there can be no doubt that an important manufactory of wrought flints existed during the polished-stone epoch. A considerable number of hatchets and other implements have been found there; all of them being either unfinished, defective, or scarcely commenced. We here give a representation (fig. 109) of a spear-head which came from this settlement. [Illustration: Fig. 109.--Spear-head from Spiennes.] Sometimes these workshops were established in caverns, and not in the open air. We are told this by M. J. Fournet, a naturalist of Lyons, in his work entitled, 'Influence du Mineur sur la Civilisation.'