The Elements of Astronomy: Or, The World as it Is, and as it AppearsCrocker and Brewster, 1850 - 376 pages |
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Page 16
... half the circumference of a great circle ; but the spherical distance of any other two points is less than a semi - circumference , being always the lesser of the two arcs into which they divide the great circle which passes through ...
... half the circumference of a great circle ; but the spherical distance of any other two points is less than a semi - circumference , being always the lesser of the two arcs into which they divide the great circle which passes through ...
Page 28
... half way between the man and the eye . The inverted image of the man will be formed fifty feet behind the lens , of the same size as the object . This image can be seen by the eye placed six inches behind it with great distinctness ...
... half way between the man and the eye . The inverted image of the man will be formed fifty feet behind the lens , of the same size as the object . This image can be seen by the eye placed six inches behind it with great distinctness ...
Page 31
... half a degree , and an equatorial star will cross it in two minutes . The moon's diameter is 30 ' , it will therefore fill the field of such a telescope , and the whole moon , from the time one edge enters till the other leaves , will ...
... half a degree , and an equatorial star will cross it in two minutes . The moon's diameter is 30 ' , it will therefore fill the field of such a telescope , and the whole moon , from the time one edge enters till the other leaves , will ...
Page 39
... half degrees from the pole , is usually chosen for this purpose . Both its culminations taking place at great and not very different altitudes , the refractions are nearly equal . Its brightness also allows it to be easily observed in ...
... half degrees from the pole , is usually chosen for this purpose . Both its culminations taking place at great and not very different altitudes , the refractions are nearly equal . Its brightness also allows it to be easily observed in ...
Page 48
... half an hour before and after meridian . By means of a windlass , and a most skilful adjustment of chains and counterpoising weights , it can also be brought to the zenith , or turned fairly round from south to north . Enormous as are ...
... half an hour before and after meridian . By means of a windlass , and a most skilful adjustment of chains and counterpoising weights , it can also be brought to the zenith , or turned fairly round from south to north . Enormous as are ...
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.