Note 25 — APPENDIX.
Reading edition
In adopting Mr. Babbage's arguments I have varied their form. Mr. Babbage takes the square of 90° and divides it into three parts, viz.:
Angle of relief 3° Angle of edge 60° Angle of escape 27° 90°
The angle of escape is thus estimated from the horizontal line perpendicular to a base line presented by the surface of the work or by a tangent to it. But as the value of this angle depends directly on its relation to the base line, and has only a complementary relation to the horizontal line, I have thought it better to confine the illustration to the same base as being more directly connected with the wedge-like action of the edge.