The elements of astronomy, physical and geometrical (1715)
Gregory, David, 1659-1708, Halley, Edmond, 1656-1742. Synopsis of the astronomy of comets, Adams, John, 1735-1826, former owner. BRL, Boston Public Library (John Adams Library) BRL · London : Printed for J. Nicholson ... and sold by J. Morphew ... · leaf 113
nt P,(ind a Diameter as\¥^he draivn parallel to it, throthe Center C; the portion EP, of the Right line S P,joining either of the Foci (as S) and the foint of ConiaBy is e^ual to half the greater Axe C A. Thro the other Focus F, draw FHparallel toP Ry meeting 5 P in H. Becaufe fby Frof. 48.lik ^.… … Bookl. of Astronomy. 79 caufe 5 C is equal to C F; and iince S His thediflFerence of the Right lines P 5, PH, it willUkewiie be the difFerence of the lines PS, P F;and E H, half this difFerence. And there-fore ?Ey ( made up of the leffer and half thedifference) is equal to half the Sum of P S,…
Astronomy
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