Astronomy for Students and General Readers

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H. Holt, 1880 - 512 oldal
 

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136. oldal - The change of motion is proportional to the motive force impressed; and is made in the direction of the right line in which that force is impressed.
136. oldal - Every body continues in its state of rest, or of uniform motion in a right line, unless it is compelled to change that state by forces impressed upon it.
141. oldal - that every particle of matter in the universe attracts every other particle, with a force whose direction is that of the line joining the two, and whose magnitude is directly as the product of their masses, and inversely as the square of their distances from each other.
136. oldal - To every action there is always opposed an equal reaction: or, the mutual actions of two bodies upon each other are always equal, and directed to contrary parts.
172. oldal - THE MOON. The mean distance of the moon from the earth is about 60 radii of the latter, while, as we have just seen, the length EV of the earth's shadow is 217 radii of the earth. Hence when the moon passes through the shadow she does so at a point less than three tenths of the way from E to V. The radius of the shadow here will be ^-Vf^4 of the radius EB of the earth, a quantity which we readily find to be about 4600 kilometres.
242. oldal - Its satellite system also deserves careful observation, especially in respect to the eclipses which occur; since we find in them a measure of the time required for light to cross the orbit of the earth, and so of the solar parallax, and also because, as has been already mentioned, they furnish a test of the constancy of the earth's rotation. The photometric method of observing these eclipses, first instituted by Professor Pickering at Cambridge in 1878, and since re-invented by Cornu in Paris, has...
v. oldal - To facilitate its use by students of different grades, the subject-matter is divided into two classes, distinguished by the size of the type. The portions in large type form a complete course for the use of those who desire only such a general knowledge of the subject as can be acquired without the application of advanced mathematics. The portions in small type comprise additions for...
461. oldal - ... 85 The shining fluid might exist independently of stars. The light of this fluid is no kind of reflection from the star in the centre. If this matter is self-luminous...
219. oldal - Considering the problem as a geometrical one, it is evident that, owing to the parallax of Venus being nearly four times as great as that of the sun, its path across the sun's disk will be different when viewed from different points of the earth's surface. The further south we go, the further north the planet will seem to be on the sun's disk. The change will be determined by the difference between the parallax of Venus and that of the sun, and this makes the geometrical explanation less simple than...
482. oldal - Herschel says, it is very probable, that the great stratum, called the Milky Way, is that in which the sun is placed*, though perhaps not in the centre of its thickness, but not far from the place where some smaller stratum branches from it. Such a supposition will satisfactorily, and with great simplicity, account for all the phenomena of the Milky Way, which, according to this hypothesis, is no other than the appearance of the projection...

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