Brocklesby, John, 1811-1889. [from old catalog] · New York, Sheldon and company · leaf 190
an exact cone, the base ot 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 of… … drawn from the centre of the sphere to that point, theiine 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 suns horizontal parallax, (Art. 94,) and AES which isthe surfs apparent semi-diameter. In…
Astronomy
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