Mechanical drawing self-taught: comprising instructions in the selection and preparation of drawing instruments, elementary instruction in practical mechanical drawing together with examples in simple geometry and elementary mechanism, including screw threads, gear wheels, mechanical motions, engines and boilers (1883)
ithin less than a division, we subdivide thatdivision as by arcs a, b, which divide it into threeequal divisions, of which the lines occupy one division.Hence, it is clear that they are at an angle of 20degrees, because twenty is one-third of sixty. Whenthe number of degrees of angle between two… … an acute angle, while B and C are at an obtuse angle.F and G form an acute angle one to the other, as alsodo G and B, while H and A are at an obtuse angle.Between I and J there are 90 degrees of angle;hence they form neither an acute nor an obtuseangle, but what is termed a right-angle, or an…
Mechanical drawing
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