Outlines of Astronomy |
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Page 43
... difference of level , accompanied , as it must be , with a difference of density in the aërial strata , must also have , corresponding to it , a certain amount of re- fraction ; less , indeed , than what would be produced by the whole ...
... difference of level , accompanied , as it must be , with a difference of density in the aërial strata , must also have , corresponding to it , a certain amount of re- fraction ; less , indeed , than what would be produced by the whole ...
Page 55
... difference of angular position of P , with respect to the invariable direction ABD , when viewed from A and from B , is the difference of the two angles DBP and DAP ; now , DBP being the exte- rior angle of the triangle ABP , is equal ...
... difference of angular position of P , with respect to the invariable direction ABD , when viewed from A and from B , is the difference of the two angles DBP and DAP ; now , DBP being the exte- rior angle of the triangle ABP , is equal ...
Page 56
... difference of the results , of his change of distance from them arising from his change of place , although that difference may be so small as to pro- duce no change in their general aspect to his unassisted sight . This is one of the ...
... difference of the results , of his change of distance from them arising from his change of place , although that difference may be so small as to pro- duce no change in their general aspect to his unassisted sight . This is one of the ...
Page 72
... difference from exact parallelism is so small that it may be practically disregarded . ' To a spectator looking upwards such a system of plumb - lines will appear to converge to his zenith ; downwards , to his nadir . ( 117. ) So also ...
... difference from exact parallelism is so small that it may be practically disregarded . ' To a spectator looking upwards such a system of plumb - lines will appear to converge to his zenith ; downwards , to his nadir . ( 117. ) So also ...
Page 73
... difference of longitudes of the places . ( 122. ) Vice versa - the interval elapsing between two different stars coming on the meridian of one and the same place , expressed in sidereal time , is the measure of the difference of right ...
... difference of longitudes of the places . ( 122. ) Vice versa - the interval elapsing between two different stars coming on the meridian of one and the same place , expressed in sidereal time , is the measure of the difference of right ...
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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...