On French-millstone-makers' phthisis / by Thomas B. Peacock, M.D.

  • Peacock, Thomas B. (Thomas Bevill), 1812-1882.
Date:
1862
Catalogue details

Licence: Public Domain Mark

Credit: On French-millstone-makers' phthisis / by Thomas B. Peacock, M.D. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    the best. The smaller portions are cut into carreaux, or quad- rangular blocks, and are extensively exjJorted to England and America. Though the masses sufficiently large to form entire stones are occasionally brought to this country, it is usually in the form of the smaller blocks, measuring about fifteen or sixteen inches in length, ten or eleven in breadth, and six or seven in depth, that the burr is seen in the millstone-makers' yards. The stone is not only brought from La Ferte sous Jonarre, but also from the neigh- bourhood of Epernon, to the south-west of Paris, and it is said to exist extensively in other parts of France.* The stones are of a yellowish brown colour, and are more or less thickly studded with small cellular or tubular spaces of irregular form, and lined by a yellowish powder. They are stated sometimes to contain fossil shells,—different quarries differing in this respect. The stones also vary in the degree of translucency. From the carreaux, or blocks, the millstones are manufactured in this country by cutting their sui'faces into angular forms, so as to fit them together, cementing the portions with plaster of Paris, and binding the whole with sti'ong bands of iron round the circum- ference ; grooves, radiating from the central opening towards the circumference, and about an inch and a half apart, are then cut on the grinding surfaces. The rough working of the stones is eflFected by a steel chisel, the pritchell, which is struck by a metal hammer, and the s\ir- faces are finished by picking with a double-pointed steel instru- ment fixed in a wooden handle—the bill and thrift. As the burr is extremely hard, every stroke of the chisel is attended hj a bright fiash of light, and a cloud of dust and larger or smaller particles of stone, forming a sharp grit, are thrown ofi. Portions of the stone and of iron from the chisel, not unfrequently become * According to Brard (Min^ralogie Appliqiice aux Arts, Paris, 1821), the silex molaire is obtained at Tarterai prfes de la Fert(S sous Jouarre, Depart- ment du Seine et Marnej Domme, Department de la Dordognej Ferte sur Loire, prfes de Nevers, Departement de la Nifevre; and Saint Maxient, De- partement des deux Sevres.