A Treatise on Astronomy: Illustrated with Maps and PlatesE. Hunt & Company, 1837 - 288 страница |
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Страница 52
... miles ; while in Peru , near the equator , the length of a degree is little more than 683 miles . Degrees of latitude have also been measured , with great care , at various intermediate latitud s , and in many cases a correspond ...
... miles ; while in Peru , near the equator , the length of a degree is little more than 683 miles . Degrees of latitude have also been measured , with great care , at various intermediate latitud s , and in many cases a correspond ...
Страница 53
... miles , 3 of which , equals the polar diameter , which is 26 miles less than the equatorial , the latter being 7,925 and the former 7,899 miles . ( 85. ) The diameter of the earth , setting aside its departure from a perfect sphere ...
... miles , 3 of which , equals the polar diameter , which is 26 miles less than the equatorial , the latter being 7,925 and the former 7,899 miles . ( 85. ) The diameter of the earth , setting aside its departure from a perfect sphere ...
Страница 54
... mile gives the diameter a c , which is thus found to equal 7920 miles . ( 86. ) It is evident from the the above prop . that a bisa mean proportional between bc and bn , that is bn : ab :: ab : bcorac nearly . Hence this simple method ...
... mile gives the diameter a c , which is thus found to equal 7920 miles . ( 86. ) It is evident from the the above prop . that a bisa mean proportional between bc and bn , that is bn : ab :: ab : bcorac nearly . Hence this simple method ...
Страница 55
... miles , that is , the 60th part of a degree of a great circle of the earth ; and in English miles , or those in common use . All degrees of latitude , - and of longitude on the equator , contain 60 geo- graphical miles . TABLE . I. Deg ...
... miles , that is , the 60th part of a degree of a great circle of the earth ; and in English miles , or those in common use . All degrees of latitude , - and of longitude on the equator , contain 60 geo- graphical miles . TABLE . I. Deg ...
Страница 58
... miles from the earth , that all indications of its existence beyond this extent cease . It is sup- posed however to exist in an extremely rarefied state , much higher . ( 92. ) From the science of Optics , we learn that a ray of light ...
... miles from the earth , that all indications of its existence beyond this extent cease . It is sup- posed however to exist in an extremely rarefied state , much higher . ( 92. ) From the science of Optics , we learn that a ray of light ...
Чести термини и фразе
altitude amount angle angular distance annual parallax apogee apparent diameter apparent magnitude ascertained astronomers attraction called cause celestial pole celestial sphere centre of gravity circle comet consequently constellation declination degrees described difference Digits eclipsed direction disc Dominical letter earth earth's axis earth's orbit earth's shadow earth's surface east equal equator equinoctial evident explain fig FIGURE greater greatest heavenly body heavens hemisphere Herschel horizon illustrated by fig increases Jupiter latitude latter length less light longitude lunar eclipse magnitude mean solar meridian miles months moon moon's orbit moving nearly nebulæ node north pole obliquity observed parallax pass perigee period plane Planisphere precession radius represent retrograde retrograde motion revolve right ascension rotation Saturn seen sidereal sidereal day solar days solar eclipse solstice south pole stars stationary sun's Suppose synodic revolution take place tides tion Uranus variation velocity Venus vernal equinox visible zenith
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Страница 142 - Aries the Ram, Taurus the Bull, Gemini the Twins, Cancer the Crab, Leo the Lion, Virgo the Virgin, Libra the Balance, Scorpio the Scorpion, Sagittarius the Archer, Capricornus the Goat, Aquarius the Waterbearer, and Pisces the Fishes...
Страница 163 - On the other hand, in the regions beneath the dark side, a solar eclipse of fifteen years in duration, under their shadow, must afford (to our ideas) an inhospitable asylum to animated beings, ill compensated by the faint light of the satellites. But we shall do wrong to judge of the fitness or unfitness of their condition from what we see around us, when, perhaps, the very combinations which convey to our minds only images of horror, may be in reality theatres of the most striking and glorious displays...
Страница 165 - Venus a pea, on a circle 284 feet in diameter; the Earth also a pea, on a circle of 430 feet; Mars a rather large pin's head, on a circle of 654 feet; Juno, Ceres, Vesta, and Pallas, grains of sand, in orbits of from 1000 to 1200 feet; Jupiter a moderate-sized orange, in a circle nearly half a mile across...
Страница 20 - The circumference of every circle is supposed to be divided into 360 equal parts, called degrees ; each degree into 60 equal parts, called minutes ; and each minute into 60 equal parts, called seconds.
Страница 228 - In the solitude of the seas, we hail a star as a friend from whom we have long been separated. Among the Portuguese and the Spaniards peculiar motives seem to increase this feeling; a religious sentiment attaches them to a constellation, the form of which recalls the sign of the faith planted by their ancestors in the deserts of the New World.
Страница 228 - It has been observed at what hour of the night, in different seasons, the Cross of the South is erect or inclined. It is a time-piece that advances very regularly near four minutes a day, and no other group of stars exhibits, to the naked eye, an observation of time so easily made.
Страница 248 - Thus a yellow colour predominating in the light of the brighter star, that of the less bright one in the same field of view will appear blue ; while, if the tint of the brighter star verge to crimson, that of the other will exhibit a tendency to green — or even appear as a vivid green, under favourable circumstances.
Страница 54 - If from any point without a circle two straight lines be drawn, one of which cuts the circle, and the other touches it ; the rectangle contained by the whole line which cuts the circle, and the part of it without the circle, shall be equal to the square of the line which touches it.
Страница 165 - ... 430 feet; Mars a rather large pin's head, on a circle of 654 feet; Juno, Ceres, Vesta, and Pallas, grains of sand, in orbits of from 1000 to 1200 feet; Jupiter a moderate-sized orange, in a circle nearly half a mile across; Saturn a small orange, on a circle of four-fifths of a mile...
Страница 248 - In such instances, the larger star is usually of a ruddy or orange hue, while the smaller one appears blue or green, probably in virtue of that general law of optics, which provides, that when the retina is under the influence of excitement by any bright, coloured light ; feebler lights, which seen alone would produce no sensation but of whiteness, shall for the time appear coloured with the tint complementary to that of the brighter.