Brinkley's Astronomy |
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Common terms and phrases
aberration accuracy altitude angular distance Aphelion apparent motion appear ascertained astronomers atmosphere attraction axis azimuth called celestial bodies celestial pole celestial sphere centre circle comet computed concave surface consequently declination diameter direction disc diurnal motion earth earth's orbit eccentricity ecliptic elongation equal equator equinox error fixed stars gravity greater greatest hemisphere Hence horizon inclination inferior conjunction inferior planets instrument interval Jupiter known latitude length light longitude lunar magnitude mean motion measured Mercury meridian method miles moon moon's move nebulæ Newton node object observed opposite parallax parallel passing Perihelion periodic perpendicular pole position quadrant radius rays refraction revolve right angles right ascension rotation round the sun satellites Saturn seen shadow sidereal solar spectrum sphere spherical spots subtends sun's superior planet supposed tance tangent telescope tion transit transit of Venus triangle velocity Venus vernier vertical visible zenith distance
Popular passages
Page 10 - Declination is either north or south, according as the object is on the north or south side of the equator. North declination is generally regarded as positive, and south declination as negative.
Page 283 - The third law, that the squares of the periodic times are as the cubes of the distances, is a property which belongs to the bodies describing elliptic orbits under the conditions just stated.
Page 278 - ... a vacuum, without the mediation of anything else, by and through which their action and force may be conveyed from one to another, is to me so great an absurdity, that I believe no man who has in philosophical matters a competent faculty of thinking, can ever fall into it. Gravity must be caused by an agent acting constantly according to certain laws ; but whether this agent be material or immaterial, I have left to the consideration of my readers.
Page xiii - It is shown in astronomy that the elevation of the celestial pole is equal to the latitude of the place, and...
Page 82 - The node through which the planet passes from the southern to the northern side of the ecliptic, is called the ascending node, and the other the descending node.
Page 62 - ... that the squares of the periodic times of the planets are proportional to the cubes of their mean distances from the sun.
Page 231 - ... yards, and in latitude 50° = 121,413. Thus the degrees appeared to diminish as the latitude increased, instead of the contrary. For it is evident that if the curvature of the earth diminish as we recede from the equator toward the poles, the degrees of latitude ought to increase, because the less the curvature, the greater space must be gone over to change the elevation of the pole by one degree. This result therefore appeared to contradict Newton's conclusion, that the earth was nearly an oblate...
Page 197 - ... the squares of the periodic times are as the cubes of the distances from the common centre, the centripetal forces will be inversely as the squares of the distances.
Page 189 - ... its disadvantages. One is, the great exactness requisite in observing the distance of the moon from the sun or star, as a small error in the distance makes a considerable error in the longitude. The moon moves at the rate of about a degree in two 1 92.
Page 233 - ... yards. The measurement in England, which was begun with a reference only to the relative situations of the observatories of Greenwich and Paris, was extended to a survey of the whole kingdom. This, General Roy having died, was conducted by Colonel Mudge, with great skill and assiduity. In the course of his survey, in the year 1801, he measured an arc of the meridian, between Dunnose in the Isle of Wight and Clifton in Yorkshire. The difference of latitude (nearly three degrees) was ascertained...