. A treatise on steel : comprising its theory, metallurgy, properties, practical working, and use. sult is the double cut and the production of a quan-tity of sharp teeth. The files for wood or rasps are not cut with a widechisel, and the indentations do not occupy all thewidth of the file. A triangular-pointed chisel struckobliquely to the face of the file, raises a small toothat every blow. Their number and their heightcorrespond to the fineness of the rasp and to thework it will have to perform. 262 TEEATISE ON STEEL. 436. In various countries many attempts have beenmade to replace, by a re

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. A treatise on steel : comprising its theory, metallurgy, properties, practical working, and use. sult is the double cut and the production of a quan-tity of sharp teeth. The files for wood or rasps are not cut with a widechisel, and the indentations do not occupy all thewidth of the file. A triangular-pointed chisel struckobliquely to the face of the file, raises a small toothat every blow. Their number and their heightcorrespond to the fineness of the rasp and to thework it will have to perform. 262 TEEATISE ON STEEL. 436. In various countries many attempts have beenmade to replace, by a regular machine, the uncer-tainty of manual labor. But none of these machineshaving been completely satisfactory, we will abstainfrom mentioning them, and also of a process byelectricity, for which we obtained a patent in 1857. 437. After cutting, the steel of the file is too soft;and in order to perfect the instrument, it must behardened according to the principles already ex-plained. 438. The heating furnace for hardening, seen inthe next figure, is very primitive in its construction, Fig. MWWWM lilWH 1 llll«lirl m ||»llOillPH ||||llll!IH!li!liii| gm« I I %> hi;,;.;,:;

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Keywords: ., bookcentury1800, bookdecade1860, bookidtreatiseonst, bookyear1868