Page:Popular Science Monthly Volume 10.djvu/187

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175
MORE CONCERNING MECHANICAL TOOLS.

sired, but shall enable it to be used with equal facility upon a broad as upon a narrow surface.

Given a rough piece of timber, nine inches wide and five feet long, to be smoothed by tools guided only by the handicraft skill of the workman, setting aside the adze as dangerous and unsuitable, the

PSM V10 D187 Heavy duty shear with base.jpg
Fig. 4.

probability is, that the tools selected would be gouges and chisels of various breadths and curvatures. The order of use would probably be, first, the narrow and deeply-curved gouges, , these to be followed by the shallower and broader, , these again to be followed by the chisels, using in the first place a chisel wider than a b. Let us consider what these tools would respectively accomplish if the timber is rough, as from the axe or pit-saw. The small gouge would corrugate the surface, ⌣⌣⌣⌣ the second gouge would enlarge the corrugation to this, ⌣⌣⌣⌣ and the chisel might render

PSM V10 D187 Two handled chisel or scraper.jpg
Fig. 5.

these more irregular. Such considerations as these, combined doubtless with others, led to the designing of what may be generally called the "guide principle," and this has been extended to various branches of artisan labor. At present we are only concerned with the application of this principle to gouges and chisels. This guide principle may consist of a guide as to the depth of cut, or as to the form of the