Worthen, William Ezra, 1819-1897, [from old catalog] ed · New York, Appleton · leaf 151
ons of two points in the lower curve, whichis entirely hidden by the sphere. The points referred to are projected ver-tically upon the line a h 2X e and/. The upper curve, which is seen in bothprojections, is obtained by a similar process; but it is to be observed that thehorizontal cutting planes… … Fig. 272. ORTHOGRAPHIC PROJECTION. 135 penetration. For this purpose, conceive a vertical plane passing through theaxis of the cone and the centre of the sphere; its horizontal projection willbe the straight line C L, joining the centres of the two bodies. Supposethis plane to be turned upon the…
Mechanical drawing
Internet Archive · Library of Congress · Public Domain Mark 1.0. Free to use for anything.
![An illustration from Nicolai Copernici Torinensis De reuolutionibus orbium coelestium, libri VI : Habes in hoc opere iam recens nato, & aedito, studiose lector, motus stellarum, tam fixarum, quàm erraticarum, cum ex ueteribus, tum etiam ex recentibus obseruationibus restitutos: & nouis insuper ac admirabilibus hypothesibus ornatos. Habes etiam tabulas expeditissimas, ex quibus eosdem ad quoduis tempus quàm facillime caculare poteris. Igitur eme, lege, fruere. [Line in Greek] (1543)](https://img.insideoutlibrary.com/img/200/ia-nicolaicopernici00cope-237-146.webp)
