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Page 110
... spectrum . To overcome the spherical aberra- tion James Gregory , ' of Aberdeen and Edin- burgh , in 1663 , in his Optica Promota , proposed a reflecting speculum of parabolic form . But it was Newton , about 1666 , who first made a re ...
... spectrum . To overcome the spherical aberra- tion James Gregory , ' of Aberdeen and Edin- burgh , in 1663 , in his Optica Promota , proposed a reflecting speculum of parabolic form . But it was Newton , about 1666 , who first made a re ...
Page 114
... spectrum . These are the Frauenhofer lines , some of which he named by the letters of the alphabet . The D line is a very marked one in the yellow . These dark lines in the solar spectrum had already been observed by Wollaston.1 On ...
... spectrum . These are the Frauenhofer lines , some of which he named by the letters of the alphabet . The D line is a very marked one in the yellow . These dark lines in the solar spectrum had already been observed by Wollaston.1 On ...
Page 115
... spectrum is a bright yellow line agreeing in position with line D of the solar spectrum . In 1832 Sir David Brewster found some of the solar black lines increased in strength to- wards sunset , and attributed them to absorption in the ...
... spectrum is a bright yellow line agreeing in position with line D of the solar spectrum . In 1832 Sir David Brewster found some of the solar black lines increased in strength to- wards sunset , and attributed them to absorption in the ...
Page 117
... spectrum of a star alongside a spectrum of hydrogen , we may see all the lines , and be sure that there is hydrogen in the star ; yet the lines in the star - spectrum may be all slightly displaced to one side of the lines of the ...
... spectrum of a star alongside a spectrum of hydrogen , we may see all the lines , and be sure that there is hydrogen in the star ; yet the lines in the star - spectrum may be all slightly displaced to one side of the lines of the ...
Page 130
... spectrum . But Rowland , of Balti- more , after having perfected the art of making . true gratings with equidistant lines ruled on metal for producing spectra , then proceeded to make a map of the solar spectrum on a large scale . In ...
... spectrum . But Rowland , of Balti- more , after having perfected the art of making . true gratings with equidistant lines ruled on metal for producing spectra , then proceeded to make a map of the solar spectrum on a large scale . In ...
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accurate Airy ancient astron Astronomer Royal astronomical units bright calculations Cape catalogue centre century Chaldæans Chinese comet Copernicus diameter discovered discovery earth Egyptian epicycles equatorial error excentric explain fact fixed stars Galileo Greenwich Halley heavenly bodies heavens heliometer Hipparchus History of Astronomy instruments JOHANNES KEPLER John Herschel Jupiter Jupiter's Kepler Laplace Lick Observatory light line of apses line of sight lunar Mars mathematical mean distance mean motion measured ment Mercury meteor miles a second moon moon's nebulæ Newton observations Observatory orbit parallax period photographic physical planet planetary pole position predicted proper motion proved Ptolemy R. S. Phil records refractor retrograde retrograde motion revolving round ring rotation satellites Saturn seems showing Sir William Herschel Sirius solar eclipse solar system spectra spectroscope spectrum sphere spots stellar sun-spot supposed tables telescope theory tion Trans Tycho Brahe universal gravitation Uranus velocity Venus Verrier
Popular passages
Page 67 - 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.
Page 26 - So he sate and cunningly guided the craft with the helm, nor did sleep fall upon his eyelids, as he viewed the Pleiads and Bootes, that setteth late, and the Bear, which they likewise call the Wain, which turneth ever in one place, and keepeth watch upon Orion, and alone hath no part, in the baths of Ocean. This star, Calypso, the fair goddess, bade him to keep ever on the left as he traversed the deep.
Page 53 - The third, viz. that the squares of the periodic times are proportional to the cubes of the mean distances...
Page 79 - Wherefore if according to what we have already said it should return again about the year 1758, candid posterity will not refuse to acknowledge that this was first discovered by an Englishman.
Page 122 - ... They have not been regarded as so successful as his geometrical analysis of the observed phenomena. It is only just to add that he himself did not attach equal weight to them ; for in answer to objections urged by Lalande to his theory that the spots are depressions, Wilson wrote thus in 1783 : — ' Whether their first production and subsequent numberless changes depend upon the eructation of elastic vapours from below, or upon eddies or whirlpools commencing at the surface, or upon the dissolving...
Page 51 - He then said boldly that it was impossible that so good an observer as Tycho could be wrong by eight minutes* and added, " out of these eight minutes we will construct a new theory that will explain the motions of all the planets.