This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1850 Excerpt: ... this very circumstance that they are near their perihelion. Their light is at first very feeble, but becomes gradually more vivid, until it sometimes surpasses that, of the brightest planets; after which it declines by the same degrees until it becomes imperceptible. We are hence led to the conclusion that comets, ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1850 Excerpt: ... this very circumstance that they are near their perihelion. Their light is at first very feeble, but becomes gradually more vivid, until it sometimes surpasses that, of the brightest planets; after which it declines by the same degrees until it becomes imperceptible. We are hence led to the conclusion that comets, coming from the remote regions of the heavens, approach, in many instances, much nearer the sun than the planets, and then recede to much greater distances. " Since comets are bodies which seem to belong to our planetary Orbits of system, it is natural to suppose that they move about the sun like cometsplanets, but in orbits extremely elongated. These orbits must, therefore, still be ellipses, having their foci at the center of the sun, but having their major axes almost infinite, especially with respect to us, who observe only a small portion of the orbit, namely, that in which the comet becomes visible as it approaches the sun. Accordingly the orbits of comets must take the form of a parabola, for we thus designate the curve into which the ellipse passes, when indefinitely elongated. " If we introduce this modification into the laws of Kepler, which The parallaxes of comets are known to be small, by two observers, at distant stations on the earth, comparing their observations taken on the same comet at near the same time. At the times the observations are made, neither observer can know how great the parallax is. It is only afterward, when comparisons are made, that judgment, in this particular, can be formed; and it is not common that any more definite conclusion can be drawn, than tliat the parallax is small, and, of coursg, the body distant Chap. Xtl. relate to the elliptical motion, we obtain those of the parabolic motion of comet...
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Add this copy of A Treatise on Astronomy, Descriptive, Physical, and to cart. $27.47, new condition, Sold by Ingram Customer Returns Center rated 5.0 out of 5 stars, ships from NV, USA, published 2006 by University of Michigan Library.
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Add this copy of A Treatise on Astronomy, Descriptive, Physical, and to cart. $54.46, good condition, Sold by Bonita rated 4.0 out of 5 stars, ships from Newport Coast, CA, UNITED STATES, published 2005 by Scholarly Publishing Office, U.
