George Iles, Inventors at Work, with Chapters on Discovery
“ Descended from his flint knife is the abounding variety of steel cutting tools all the way from the razor, concave on both sides, to the axe, doubly convex. As the arts have become more specialized, as artificial power has been introduced, the contrasts of the form of one tool with another have grown more and more striking. The bar which slices metal is stout of build, and rectangular in section, while a lancet is little wider or thicker than a [90] blade of grass. The knives which divide leather, rubber, and rope, differ much from one another ”
