A Treatise on AstronomyCarey, Lea & Blanchard, 1835 - 396 σελίδες |
Άλλες εκδόσεις - Προβολή όλων
Συχνά εμφανιζόμενοι όροι και φράσεις
altitude amount angle angular angular velocity appear arise ascertained astronomical atmosphere attraction axis bright calculation called cause celestial centre circle comet described determined deviation difference direction disc distance disturbed body disturbing force diurnal diurnal motion double stars earth earth's surface eccentricity ecliptic effect ellipse equal equator equinox error exact exactly fact fixed former globe gravity heavens heliocentric horizon inclination inequality instance instrument interval Jupiter latitude latter law of Kepler length less light longitude lunar magnitude mass mean measure meridian moon moon's nearly nodes nutation object observed parallax perihelion period perpendicular planet planetary pole portion position precession produced proportion radius recess remarkable retrograde revolution revolving right ascension ring rotation round satellites Saturn seen sidereal sidereal period situation solar solar eclipse sphere spherical stars station sun's suppose synodical period telescope tion Uranus variation velocity Venus visible whole zenith
Δημοφιλή αποσπάσματα
Σελίδα 225 - that every particle of matter in the universe attracts every other particle, with a force whose direction is that of the line joining the two, and whose magnitude is directly as the product of their masses, and inversely as the square of their distances from each other.
Σελίδα 195 - They commence at the vernal equinox, and are named in order — Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricornus, Aquarius, Pisces.* They are denoted also by the following symbols : — <y>j 8, n , 93, SI, ITR, A, -n\_, / , Vj", *:, X.
Σελίδα 11 - Admission to its sanctuary, and to the privileges and feelings of a votary, is only to be gained by one means — sound and sufficient knowledge of mathematics, the great instrument of all exact inquiry, without which no man can ever make such advances in this or any other of the higher departments of science as can entitle him to form an independent opinion on any subject of discussion within their range.
Σελίδα 368 - This earth ? reciprocal, if land be there, Fields and inhabitants. Her spots thou seest As clouds, and clouds may rain, and rain produce Fruits in her soften'd soil, for some to eat Allotted there ; and other suns, perhaps, With their attendant moons, thou wilt descry, Communicating male and female light, Which two great sexes animate the world, Stored in each orb, perhaps, with some that live...
Σελίδα 201 - The sun's rays are the ultimate source of almost every motion which takes place on the surface of the earth. By its heat are produced all winds, and those disturbances in the electric equilibrium of the atmosphere which give rise to the phenomena of lightning, and probably also to those of terrestrial magnetism and the aurora.
Σελίδα 201 - ... of those great deposits of dynamical efficiency which are laid up for human use in our coal strata. By them the waters of the sea are made to circulate in vapour through the air, and irrigate the land, producing springs and rivers. By them are produced all disturbances of the chemical equilibrium of the elements of nature, which, by a series of compositions and decompositions, give rise to new products, and originate a transfer of materials.
Σελίδα 383 - Every year whose number is not divisible by 4 without remainder, consists of 365 days ; every year which is so divisible, but is not divisible by 100, of 366 ; every year divisible by 100, but not by 400, again of 365 ; and every year divisible by 400, again of 366.
Σελίδα 356 - Useful, it is true, they are to man as points of exact and permanent reference ; but he must have studied astronomy to little purpose, who can suppose man to be the only object of his Creator's care, or who does not see in the vast and wonderful apparatus around us provision for other races of animated beings. The planets, as we have seen, derive their light from the sun; but that cannot be the case with the stars. These doubtless, then, are themselves suns, and may, perhaps, each in its sphere,...
Σελίδα 263 - Again, the intensity of gravity, or its efficacy in counteracting muscular power and repressing animal activity, on Jupiter, is nearly two and a half times that on the Earth, on Mars not more than one-half, on the Moon one-sixth, and on the smaller planets probably not more than one-twentieth; giving a scale of which the extremes are in the proportion of sixty to one.
Σελίδα 7 - ... on the credit of others. Such an effort is, in fact, a commencement of that intellectual discipline which forms one of the most important ends of all science. It is the first movement of approach towards that state of mental purity which alone can fit us for a full and steady perception of moral beauty as well as physical adaptation. It is the " euphrasy and rue " with which we must " purge our sight " before we can receive and contemplate as they are the lineaments of truth and nature.