Outlines of Astronomy |
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Page 20
... telescope , and some other of the simpler instruments . Of course , the more of such knowledge he brings to the perusal , the easier will be his progress , and the more complete the information gained ; but we shall endeavour in every ...
... telescope , and some other of the simpler instruments . Of course , the more of such knowledge he brings to the perusal , the easier will be his progress , and the more complete the information gained ; but we shall endeavour in every ...
Page 77
... telescopes to the purposes of angular measurement , every imperfection of structure of division becomes magnified by the whole optical power of that instru- ment ; and that thus , not only direct errors of workmanship , arising from ...
... telescopes to the purposes of angular measurement , every imperfection of structure of division becomes magnified by the whole optical power of that instru- ment ; and that thus , not only direct errors of workmanship , arising from ...
Page 89
... telescope is applied in astro- nomy to the precise determination of a direction in space , - that , namely , of the visual ray by which we see a star or any other distant object . ( 154. ) The telescope most commonly used in astronomy ...
... telescope is applied in astro- nomy to the precise determination of a direction in space , - that , namely , of the visual ray by which we see a star or any other distant object . ( 154. ) The telescope most commonly used in astronomy ...
Page 90
... telescope , will be necessary to vary the direction of the axis till the coincidence is rendered perfect . So precise is this mode of pointing found in practice , that the axis of a telescope may be directed towards a star or other ...
... telescope , will be necessary to vary the direction of the axis till the coincidence is rendered perfect . So precise is this mode of pointing found in practice , that the axis of a telescope may be directed towards a star or other ...
Page 91
... telescope firmly fastened on a horizontal axis directed to the east and west points of the horizon , or at right angles to the plane of the meridian of the place of observation . The extremities of the axis are formed into cylindrical ...
... telescope firmly fastened on a horizontal axis directed to the east and west points of the horizon , or at right angles to the plane of the meridian of the place of observation . The extremities of the axis are formed into cylindrical ...
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Common terms and phrases
altitude amount angle angular appear apsides ascertained astronomers axis bright calculation celestial centre circle comet curve described diameter difference direction disc distance disturbed body disturbing force diurnal diurnal motion double stars earth ecliptic effect elements ellipse epoch equal equator equinoctial equinox error exact excentricity fixed globe gravity greater heavens heliocentric horizon inclination increase inequality instance instrument interval Jupiter latitude latter less light longitude lunar magnitude mass mean measure meridian moon moon's motion nearly nebula node normal force nutation object observed orbit parallax parallel perigee perihelion period perpendicular perturbations planet planetary pole portion position precession proper motions proportion recede recess reckoned refraction remarkable respect result revolution right ascension rotation round satellites Saturn seen sidereal sidereal day sidereal period situation solar sphere spherical stars station sun's suppose syzygies tangential force telescope tion Uranus variation velocity visible whole zenith
Popular passages
Page 211 - ... of those great deposits of dynamical efficiency which are laid up for human use in our coal strata. By them the waters of the sea are made to circulate in vapour through the air, and irrigate the land, producing springs and rivers.
Page 568 - William Youatt. A new edition, with numerous illustrations ; together with a General History of the Horse ; a Dissertation on the American Trotting Horse; how trained and jockeyed; an Account of his Remarkable Performances; and an Essay on the Ass and the Mule.
Page 211 - The sun's rays are the ultimate source of almost every motion which takes place on the surface of the earth. By its heat are produced all winds, and those disturbances in the electric equilibrium of the atmosphere which give rise to the phenomena of lightning, and probably also to terrestrial action and the aurora.
Page 6 - Manual of Ancient History, from the Remotest Times to the Overthrow of the Western Empire, AD 476.
Page 281 - As to getting correct notions on this subject by drawing circles on paper, or, still worse, from those very childish toys called orreries, it is out of the question.
Page 298 - ... the earth. And since it is an observed fact, that even those larger comets which have presented the appearance of a nucleus have yet exhibited no phases, though we cannot doubt that they shine by the reflected solar light, it follows that even these can only be regarded as great masses of thin vapour, susceptible of being penetrated through their whole substance by the sunbeams, and reflecting them alike from their interior parts and from their surfaces.
Page 204 - Ingens macula in sole conspiciebatur, cujus diam eter= s'ji "diam. solis. uniformly bright. Its ground is finely mottled with an appearance of minute, dark dots, or pores, which, when attentively watched, are found to be in a constant state of change. There is nothing which represents so faithfully this appearance as the slow subsidence of some flocculent chemical precipitates in a transparent fluid, when viewed perpendicularly from above...
Page 526 - Every year whose number is not divisible by 4 without remainder, consists of 365 days ; every year which is so divisible, but is not divisible by 100, of 366 ; every year divisible by 100, but not by 400, again of 365 ; and every year divisible by 400, again of 366.
Page 166 - This remarkable belt has maintained, from the earliest ages, the same relative situation among the stars ; and, when examined through powerful telescopes, is found (wonderful to relate ! ) to consist entirely of stars scattered by millions, like glittering dust, on. the black ground of the general heavens.
Page 210 - ... may, nevertheless, be in a state of most intense ignition. It does not, however, follow of necessity that it must be so. The contrary is at least physically possible. A perfectly reflective canopy would effectually defend it from the radiation of the luminous regions above its atmosphere, and no heat would be conducted downwards through a gaseous medium increasing rapidly in density. That the penumbral clouds are highly reflective, the fact of their visibility in such a situation can leave no...