Detroit. Public schools. Dept. of instruction, teacher training and research. [from old catalog], Kepler, Frank Roy. [from old catalog] · Detroit · leaf 22
erat-ing line are the right-line elements. These right-line elements may be found on the surface ofa cone by passing a plane either through its vertex in anydirection so as to contain the axis of the cone, or through thevertex and the base of the cone in any direction. Elements thus found may be… … elements in the H projection. Project the points 2, 3, 4, 5,etc., to the base in the vertical projection as 2, 3, 5% etc.Connect the points thus found with 0, the apex. If a in Fig. 26, is the V projection of a point on one of theelements as 0-3, then its H projection may be found byprojecting its…
Projection
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![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-304-198.webp)
