The Elements of Astronomy: Or, The World as it Is, and as it AppearsCrocker and Brewster, 1850 - 376 pages |
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Page ii
... Act of Congress , in the year 1850 , BY CROCKER AND BREWSTER , In the Clerk's Office of the District Court of Massachusetts . MICROFILMED AT HARVARD PREFACE . THE apology for the present treatise on Astronomy Aste 808613.
... Act of Congress , in the year 1850 , BY CROCKER AND BREWSTER , In the Clerk's Office of the District Court of Massachusetts . MICROFILMED AT HARVARD PREFACE . THE apology for the present treatise on Astronomy Aste 808613.
Page iii
... present treatise on Astronomy is based on the nature of the subject ; it is one which re- quires to be presented to the student from more than one point of view . He should learn from the original observer , the profound generalizer ...
... present treatise on Astronomy is based on the nature of the subject ; it is one which re- quires to be presented to the student from more than one point of view . He should learn from the original observer , the profound generalizer ...
Page 29
... present short distance from the eye . But this short distance is equal to the focal length of the lens , so that the magnifying power produced by the lens is equal to six inches divided by the focal length of the lens . Such a lens is ...
... present short distance from the eye . But this short distance is equal to the focal length of the lens , so that the magnifying power produced by the lens is equal to six inches divided by the focal length of the lens . Such a lens is ...
Page 33
... present . § 47. If the dispersive powers of different media were in proportion to their refractive powers , it would be impos- sible to correct this chromatic aberration . But fortunately different media produce spectra of different ...
... present . § 47. If the dispersive powers of different media were in proportion to their refractive powers , it would be impos- sible to correct this chromatic aberration . But fortunately different media produce spectra of different ...
Page 40
... present itself in the heavens . Now a point in the sphere is determined by reference to two great circles , one of which passes through the pole of the other . On the earth the position of a place is known if we know its longitude and ...
... present itself in the heavens . Now a point in the sphere is determined by reference to two great circles , one of which passes through the pole of the other . On the earth the position of a place is known if we know its longitude and ...
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
altitude angular aphelion appear ascertained astronomical atmosphere attraction axis body called cause celestial centre of gravity centrifugal force circle cluster comet constellations curve density described diameter direction disc distance disturbing earth earth's surface eccentricity ecliptic equal equator equatorial equinoctial feet fixed stars globe greater heat heavens hemisphere Herschel horizon illuminated inclined increase inequalities John Herschel Jupiter Jupiter's latitude length less light longitude lunar mass measure meridian miles minute moon moon's move nearer nearly nebulous nodes nucleus nutation 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 system space sphere sun's suppose tail telescope tion Uranus vapor variations velocity Venus vernal equinox vertical visible whole zenith zodiacal light
Popular passages
Page 330 - ... 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 262 - But, in the midst of all these vicissitudes, the length of the major axes and the mean motions of the planets remain permanently independent of secular changes. They are so connected by Kepler's law, of the squares of the periodic times being proportional to the cubes of the mean distances of the planets from the sun, that one cannot vary without affecting the other.
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 199 - our astronomical 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 258 - 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 345 - As the moon can never be full but when she is opposite to the sun, and the sun is never in Virgo and Libra, but in our autumnal months, it is plain that the moon is never full in the opposite signs, Pisces and Aries, but in these two months. And...