Astronomical Papers Prepared for the Use of the American Ephemeris and Nautical Almanac, Volume 2

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1891
 

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Page 321 - Green and me; but the time it happened was not noted by either of us: it appeared to be very difficult to judge precisely of the times that the internal contacts of the body of Venus happened, by reason of the darkness of the penumbra at the...
Page 114 - ... FIZEAU'S paper on the subject was presented to the Academy of Sciences July 23, 1849.* We have already shown that his method and that of Galileo rest fundamentally upon the same principle. The arrangement of his 'apparatus was substantially as follows: A telescope was fixed upon a house at Suresne pointing to the hill Montmartre. On this hill was a second fixed telescope looking directly into the first, the distance between them being about 8,633 meters. In the focus of this second telescope...
Page 113 - The question then naturally arose whether the light equation, deduced on the hypothesis that the tangent of the angle of the constant of aberration was the ratio of the velocity of the earth in its orbit to the velocity of light, might not need correction or modification. This question cannot yet be considered as definitely settled, since the modifications or corrections might arise from a variety of causes. One of these causes is connected with a very delicate question in the theory of the luminiferous...
Page 1 - Formulae and Tables for Expressing Corrections to the Geocentric Place of a Planet in Terms of Symbolic Corrections to the Elements of the Orbits of the Earth and Planet
Page 321 - Fig. 5 is a representation of the appearance of Venus at the middle of the egress and ingress, for the very same phenomenon was observed at both : at the total ingress the thread of light made its appearance with an uncertainty of several seconds ; I judged that the penumbra was in contact with the Sun's limb 10...
Page 112 - The discovery of aberration by Bradley afforded an independent and yet more accurate method of determining the light equation. We call to mind that the latter constant, and that of aberration, are not to be regarded as independent of each other, but only as two entirely distinct expressions of the same result. The constant of aberration gives a relation between the velocity of light and the velocity of the earth in its orbit from which, by a very simple calculation, the time required for light to...
Page 115 - ... impossible for the reason that the flashes of light, seen through the water, would have reached the mirror at every point of its revolution ; and only an exceedingly small fraction of them could have been reflected to the eye of the observer. This difficulty was speedily overcome by Foucault and...
Page 112 - He found llm to be the time required for light to pass over a distance equal to the radius of the Earth's orbit. DOMINIQUE CASSINI while admitting that the hypothesis of ROEMER explained the observed inequality, contested its right to reception as an established theory, on the ground that the observed inequality might be a real one in the motion of the satellite itself.f Continued observation showed that the time assigned by ROEMER for the passage of light between the Earth and Sun, or " the light...
Page 113 - If, in accordance with the undulatory theory of light, we suppose the hypothetical entity called "the luminiferous medium 1 ' to be a substance, each part of which has its own definite and fixed location in space, then we must conceive that another unknown quantity may enter into the problem, namely, the motion of the heavenly bodies through this medium. We have relative motions in the solar system, exceeding 50 kilometers per second, and possibly greater relative motions among the stars.

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