The latter half of the eighteenth century furnishes a large catalogue of distinguished names, men of high scientific ability, and, for the most part, of the finest mathematical minds, by whose labors practical astronomy made vast advances, and the physical theory of the universe, as previously developed, was amply illustrated and confirmed. During this era lunar tables were constructed of sufficient accuracy to be employed to solve the great problem of the longitude at sea. This was the work of Mayer, for which his widow received the sum of £3000 from government; and since that period, the publication of such tables, showing the places of the sun and moon, with the distance of the later from certain fixed stars, for every three hours, three years in advance, has been a national object, contributing to the safety of navigators upon the trackless deep. The same period is also celebrated for the determination of the figure and magnitude of the earth, and for the great improvements made in instruments of observation. If the century opened with lustre derived from the physical demonstrations of Newton, it closed magnificently with the telescopic discoveries of Herschel, the wonderful resident by the stately battlements of Windsor, by whose mechanical skill and matchless industry new regions were added to our solar system, and views unfolded of the infinity of the firmament, and the character of its architecture, which eye had not seen or the mind conceived. A work specially devoted to the life and labors of Herschel is a desideratum. It is not to the credit of the country, that the men who have headed its physical force upon the field of battle have enjoyed a larger measure of public admiration and gratitude, and found a more speedy chronicle, than those who have enlarged the field of thought, ministered to the intellectual gratification, and elevated the mental character of the community. Bradley had lain in his grave 70 years, Newton 104, and Flamstead 116, before their memory received its meed of justice from the hands of Rigaud, Brewster, and Baily; a slackness to be attributed to the want of a due national estimate of the value of science, rather than to the reluctance of those who were competent to do ample honor to their merits. Herschel still remains without a record of this kind, though the materials for it are abundant, and his claims undoubted. Born at Hanover, the son of a musician in comparatively humble life, but early a resident in England, he appeared first as a professor and teacher of music, but rapidly rose by his own unaided efforts to eminence as an optician and astronomer. Anxious to inspect for himself the sublime revelations of the heavens, but destitute of means to purchase a telescope of sufficient power for his purpose, he resolved to employ some previous knowledge of optics and mechanics in the construction of an instrument. The earliest, a five-foot reflector,