The Elements of Astronomy: Or, The World as it Is, and as it AppearsCrocker and Brewster, 1850 - 376 pages |
From inside the book
Results 1-5 of 54
Page 25
... consider light as that vibration of an unknown fluid which causes to our eye the sensation of sight .. We cannot attain perfect certainty as to the nature of light , but we can learn its laws , and reason concerning them without this ...
... consider light as that vibration of an unknown fluid which causes to our eye the sensation of sight .. We cannot attain perfect certainty as to the nature of light , but we can learn its laws , and reason concerning them without this ...
Page 29
... consider the effect of each of these glasses upon the apparent motion and brightness of objects seen through them . Distant motions appear slow , because the space passed through subtends so small an angle at the eye . The moon wheels ...
... consider the effect of each of these glasses upon the apparent motion and brightness of objects seen through them . Distant motions appear slow , because the space passed through subtends so small an angle at the eye . The moon wheels ...
Page 30
... consider not the power of each separately , but the whole power of the tele- scope . $ 41 . Let a person direct the tubes of a telescope ( without the lenses ) to any celestial object , and there fix them ; he will soon find that in a ...
... consider not the power of each separately , but the whole power of the tele- scope . $ 41 . Let a person direct the tubes of a telescope ( without the lenses ) to any celestial object , and there fix them ; he will soon find that in a ...
Page 60
... consider how long light travelling 192,000 miles a second would be in travelling from them to us . Light is one and one quarter seconds passing from the moon to the earth ; eight minutes from the sun ; three to twelve years from the ...
... consider how long light travelling 192,000 miles a second would be in travelling from them to us . Light is one and one quarter seconds passing from the moon to the earth ; eight minutes from the sun ; three to twelve years from the ...
Page 66
... considers the course of the milky - way , according to the determination of other distinguished as- tronomers , as pointing out the plane , which is to be taken as the ground plane of the starry stratum , and he fixes . the central ...
... considers the course of the milky - way , according to the determination of other distinguished as- tronomers , as pointing out the plane , which is to be taken as the ground plane of the starry stratum , and he fixes . the central ...
Other editions - View all
The Elements of Astronomy, Or the World as It Is, and as It Appears (Classic ... Anna Cabot Lowell No preview available - 2016 |
Common terms and phrases
aberration altitude angular aphelion appear ascertained astronomical atmosphere attraction axis body called cause celestial centre of gravity centrifugal force circle cluster comet constellations curve degree density described diameter direction disc distance disturbing double star earth earth's surface eccentricity ecliptic equal equator equatorial equinoctial feet fixed stars globe greater heat heavens hemisphere horizon illuminated inclined increase inequalities Jupiter Jupiter's latitude length less light longitude lunar mass mean measure meridian miles minutes moon moon's move nearer nearly nebulous nodes nutation object obliquely observed parallax parallel passes perigee perihelion period perpendicular planets polar pole portion position proper motion proportion radius rays refraction revolution revolve right angles right ascension rise rotation satellites Saturn seen shadow side sidereal sidereal day solar eclipse solar system space sphere spherical sun's suppose telescope tion Uranus vapor variations velocity Venus vernal equinox vertical visible whole zenith
Popular passages
Page 344 - ... that the mean longitude of the first satellite, minus three times that of the second, plus twice that of the third, is always equal to two right angles.
Page 37 - Now, suppose the head of the screw to be a circle, whose diameter is an inch, the circumference of the head will be something more than three inches : this may be easily divided into a hundred equal parts distinctly visible. If a fixed index be presented to this graduated circumference, the hundredth part of a revolution of the screw may be observed, by noting the passage of one division of the head under the index. Since one entire revolution of the head moves the point through the fiftieth of an...
Page 213 - Observer' at a salary of 100£ per annum, his duty being 'forthwith to apply himself with the most exact care and diligence to the rectifying the tables of the motions of the heavens and the places of the fixed stars, so as to find out the so much desired longitude of places for the perfecting the art of navigation.
Page 22 - The Latitude of a star is its angular distance from the ecliptic measured on a circle of latitude.
Page 13 - A sphere is a solid terminated by a curved surface all the points of which are equally distant from a point within called the centre.
Page 272 - The radial force, or that part of the disturbing force which acts in the direction of the line joining the centres of the sun and disturbed planet, has no effect on the areas, but is the cause of periodical changes of small extent in the distance of the planet from the sun. It has already been shown, that the force producing perfectly elliptical motion varies inversely as the square of the distance, and...
Page 13 - The radius of a sphere, is a straight line drawn from the center to any point of the surface.
Page 38 - Now, the arc of a circle, subtended by one second, is less than the 200,000th part of the radius, so that on a circle of 6 feet in diameter it would occupy no greater linear extent than part of an inch ; a quantity requiring a powerful microscope to be discerned at all.
Page 268 - But such a personification of "force" is a remnant of barbaric thought, in no wise sanctioned by physical science. When astronomy speaks of two planets as attracting each other with a " force " which varies directly as their masses and inversely as the squares of their distances...
Page 131 - It is, therefore, partly to this cause, and partly to those we have developed above, that the slight deviations we now perceive must be attributed. " Such is a summary of the hypothesis of La Place on the origin of the solar system. This hypothesis explains, in the most satisfactory manner, the three most remarkable phenomena presented by the planetary motions. " 1st. The motion of the planets in the same direction, and nearly in the same plane.