Practical engineering drawing and third angle projection, for students in scientific, technical and manual training schools and for ... draughtsmen .. (1897)
Willson, Frederick Newton, 1855-1939 · Princeton, N.J., The author · leaf 51
any circle of the sphere; E the position of the eye: then a b, the projection of ^ 5 on plane MN^ CONIC SECTIONS. 45 (see Art. 4), is a circle, being a sub-contrary section of the visual cone E. A B, as the studentcan easilj prove. 138. We now take up the conic sections as derived from a right…
Mechanical drawing · Lettering
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