Page:Popular Science Monthly Volume 9.djvu/214

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194
THE POPULAR SCIENCE MONTHLY.

progressive condensation of fibres, and to that extent an increase in the difficulty of the work.

The equally-inclined sides of the wedge-form of edge hitherto alone described as belonging to axes, and the equal pressure this form necessarily exerts upon each side if a blow is given in the plane of the axe, suggest what will be the action of an axe if the angle of the wedge is not bisected by the middle line of the metal. Assume that one face only is inclined, and that the plane of the other is continuous to the edge, then let the blow be struck as before. It will be obvious that the plane in the line of the fibres cannot cause any separation of these fibres, but the slope entering the wood will separate the fibres on its own side. Suppose a hatchet sharpened as previously described, and one as now described, are to be applied to the same work—viz., the cutting from a solid block the outside

PSM V09 D214 Modern axe heads 1.jpg
Fig. 9. Fig. 10.

irregularities—say to chop the projecting edges from a square log and to prepare it for the lathe. It may be briefly stated that the hatchet described in the second case would do the work with greater ease to the workman, and with a higher finish, than the ordinary equally-inclined sides of the edge of the common hatchet. Coach-makers have

PSM V09 D214 Chisel head hatchet.jpg
Fig. 11.

much of this class of hatchet-paring work to do, and the tool they use is shaped as in Fig. 10. The edge is beveled on one side only, and, under where the handle enters the eye, may be noticed a piece rising toward the handle; on this the finger of the workman rests in order to steady the blade in its entrance into the timber in the plane