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action angle appears arising assumed attraction axes axis becomes bodies cause centre of gravity changes co-ordinates coefficients computed consequently constant contain curve density depending described determined differential direction distance disturbing earth eccentricity ecliptic effect elements epoch equal equation expression fluid force functions give given greater hence inclination increase inequalities integral Jupiter Jupiter's known latitude less longitude mass mean motion moon move nearly nodes observation obtained omitted orbit parallax periodic planets position preceding principal produce quantities ratio regard represented resolved result rotation satellites Saturn secular sine space square substituted supposed surface theory third tion true values variation varies velocity whence whole zero
Page lxviii - the formation of the earth was contemporaneous with that of the rest of the planets ; but they show that creation is the work of Him with whom ' a thousand years are as one day, and one day as a thousand years. 1
Page iv - of elevated meditation. The contemplation of the works of creation elevates the mind to the admiration of whatever is great and noble, accomplishing the object of all study, •which in the elegant language of Sir James Mackintosh is to inspire the love of truth, of wisdom, of beauty, especially of goodness, the highest beauty, and
Page 158 - That the squares of the periodic times of the planets are proportional to the cubes of their mean distances from the sun.
Page lvi - light or heat; its intensity diminishes as the rarity of the air increases ; so that, at a very small height above the surface of the earth, the noise of the tempest ceases, and the thunder is heard no more in those boundless regions where the heavenly bodies accomplish their periods in eternal and sublime silence.
Page l - and open sea, there is a meridian about 30° eastward of the moon, where it is always high water both in the hemisphere where the moon is, and in that which is opposite. On the west side of this circle the tide is flowing, on the east it is ebbing, and on the meridian at
Page lv - in the undulations of an elastic medium. All the principal phenomena of heat may actually be illustrated by a comparison with those of sound. The excitation of heat and sound are not only similar, but often identical, as in friction and percussion ; they are both communicated by contact and
Page xvii - refer Jupiter to a place in which he is not. His true position is in the diagonal of the parallelogram, whose sides are in the ratio of the velocity of light to the velocity of the earth in its orbit, which is as
Page xiii - a discovery,' says Professor Playfair, ' that must render the name for ever memorable in science, and revered by those who delight in the contemplation of whatever is excellent and sublime. After Newton's discovery of the elliptical orbits of the planets, La Grange's discovery of their periodical inequalities is without doubt the noblest truth in physical astronomy
Page xii - begin a new course, thus for ever oscillating about a mean value. This, however, would not be the case if the planets moved in a resisting medium, for then both the eccentricity and the major axes of the orbits would vary with the time, so that the stability of the system would be ultimately destroyed.
Page v - must dwindle into insignificance, or even become invisible ; and that not only man, but the globe he inhabits, nay the whole system of which it forms so small a part, might be annihilated, and its extinction be unperceived in the immensity of creation. A complete acquaintance with Physical Astronomy can only be attained by those who are well versed in the