# Elements of Astronomy: For the Use of Schools and Academies : with Questions

Cummings & Hilliard, 1822 - Astronomy - 116 pages

### Popular passages

Page 22 - It is from the equator that latitude on the earth is reckoned. All places between the equator and the north pole are in north latitude, and all places between the equator and the south pole are in south latitude. The latitude is greater, as the place is farther from the equator and nearer the poles.
Page 51 - A, the starting point, they were both on the same meridian, but when the fictitious sun comee to 1, and the real sun to A, they are not in the same meridian, but the real sun is westward of the fictitious one, the real sun being at A while the false sun is on the meridian 1; consequently, as the earth turns on its axis from west to east, any particular place will come under the sun's...
Page 8 - The different distances of the planets from the sun occasion a reception of different degrees of heat and light. These are received according to the square of the distance of the planet from the sun ; that is, they decrease as the square of the distance increases. /Thus, if the distance of one planet from the sun be 1, and the distance of another be 2, and of a third be 3,, the heat and light received at the first is 1 X 1 = 1, at the second 2 X 2 = 4 times less, or J, at the third 3x3 = 9 nine times...
Page 26 - Let us return to the consideration of terrestrial latitude and longitude. As the latitude of a place is its distance from the equator measured on its meridian, and all meridians are great circles and consequently equally large, it is obvious that a degree, or ,^v part, of one is equal to the same part of another.
Page 79 - The cycle of the moon, чиЬ«т. commonly called the golden number, is a revolution of 19 years ; in which time, the conjunctions, oppositions, and other aspects of the moon, are within an hour and a half of being the same as they were on the same days of the months 19 years before.
Page 45 - ... declination from the celestial equator either north or south, he shines over or beyond one pole, and not to the other. So that there is a region about one pole, which is a long time in the light hemisphere ; and a region about the other pole, which for an equal length of time is in the dark hemisphere. At the poles, there is but one day and one night in a year, each of six months. The distance to which the sun shines beyond the poles is always equal to his own declination; and as his declination...
Page 48 - ... than in summer in north latitude. From this circumstance, we might be led to suppose, that south latitude is most favourable to vegetation. But to compensate for a less degree of heat, the inhabitants in north latitude have longer summers than those in south latitude. For, by inspecting the figure, as the sun is not in the centre of the ellipse but in a focus, the earth must pass farther in going one half its orbit, than in going the other half. The earth also moves slower as it is farther from...
Page 95 - Rectify the globe for the latitude of the place, find the sun's place in the ecliptic and bring it to the brass meridian, and set the index of the hour circle to 12.
Page 44 - But as the ecliptic and the equator make an angle with each other of 23|°, the sun cannot be in the celestial equator, except at the points where the equator cuts the ecliptic, which are the beginning of the signs Aries and Libra. The sun enters these signs on the 20th March and 23d of September. Hence at these periods, and at no others, the days and nights are equal all over the world; and on this account they are called equinoxes; the first the \ vernal equinox, the second the autumnal. At these...