The Elements of Astronomy: Or, The World as it Is, and as it AppearsCrocker and Brewster, 1850 - 376 σελίδες |
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Σελίδα 20
... object from the north or south point of the horizon , re- ferred to the horizon by a vertical circle ; or it is the an- gle comprised between two vertical planes ; one passing through the elevated pole , the other through the object ...
... object from the north or south point of the horizon , re- ferred to the horizon by a vertical circle ; or it is the an- gle comprised between two vertical planes ; one passing through the elevated pole , the other through the object ...
Σελίδα 23
... objects within the circle of perpetual appa- rition come twice on the meridian above the horizon in every diurnal revolution ; once above and once below the pole . These are called their upper and lower culmina- tions . All the heavenly ...
... objects within the circle of perpetual appa- rition come twice on the meridian above the horizon in every diurnal revolution ; once above and once below the pole . These are called their upper and lower culmina- tions . All the heavenly ...
Σελίδα 27
... objects around us by light which may have been many times reflected . Reflected light is however weak , because a great ... object nearer to the eye , and thus increase its apparent size , brightness , and rapidity of motion . 35. The ...
... objects around us by light which may have been many times reflected . Reflected light is however weak , because a great ... object nearer to the eye , and thus increase its apparent size , brightness , and rapidity of motion . 35. The ...
Σελίδα 28
... object of greater size . Let us examine the effects of placing convex lenses at different distances between the eye and an object . We will suppose a man to be 100 feet from the eye . We will place a convex glass of twenty - five feet ...
... object of greater size . Let us examine the effects of placing convex lenses at different distances between the eye and an object . We will suppose a man to be 100 feet from the eye . We will place a convex glass of twenty - five feet ...
Σελίδα 29
... objects , particularly of those which are within our reach , which is of great im- portance in optics . Rays from each point of a distant ob- ject enter the eye in parallel lines , and the object is dis- tinctly seen . If we bring an object ...
... objects , particularly of those which are within our reach , which is of great im- portance in optics . Rays from each point of a distant ob- ject enter the eye in parallel lines , and the object is dis- tinctly seen . If we bring an object ...
Άλλες εκδόσεις - Προβολή όλων
The Elements of Astronomy, Or the World as It Is, and as It Appears (Classic ... Anna Cabot Lowell Δεν υπάρχει διαθέσιμη προεπισκόπηση - 2016 |
The Elements of Astronomy, Or, the World as it Is, and as it Appears Δεν υπάρχει διαθέσιμη προεπισκόπηση - 2020 |
Συχνά εμφανιζόμενοι όροι και φράσεις
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
Δημοφιλή αποσπάσματα
Σελίδα 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.
Σελίδα 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.
Σελίδα 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...
Σελίδα 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.
Σελίδα 22 - The Latitude of a star is its angular distance from the ecliptic measured on a circle of latitude.
Σελίδα 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.
Σελίδα 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...
Σελίδα 13 - The radius of a sphere, is a straight line drawn from the center to any point of the surface.
Σελίδα 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.
Σελίδα 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...