Elements of astronomy ... with explanatory notes, and questions for examination (1855)
Brocklesby, John, 1811-1889 · New York, Farmer, Brace & co. · leaf 184
ot an exact cone, the base of whichis a circle. It would be a cone if the earth was a perfect sphere but beingan ellipsoid the base of the shadow is an ellipse instead of a circle. When is an eclipse total? When partial? What is an appulse? What is theform of the shadow of a globe illumined by one… … =^W drawn from the centre of the sphere to that point, theline drawn from the centre and the touching linealways make a right angle with each other. Now joinAE, and we thus form two angles ; viz., DAE which isthe surfs horizontal parallax, (Art. 94,) and AES which isthe suns apparent semi-diameter.…
Astronomy
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