Several causes concurred about the beginning of the last century to give a fresh and powerful impulse to investigations having this end in view. The rapid progress of theory almost compelled a corresponding advance in observation; instrumental improvements rendered such an advance possible; Herschel's discoveries quickened public interest in celestial inquiries; royal, imperial, and grand-ducal patronage widened the scope of individual effort. The heart of the new movement was in Germany. Hitherto the observatory of Flamsteed and Bradley had been the acknowledged centre of practical astronomy; Greenwich observations were the standard of reference all over Europe; and the art of observing prospered in direct proportion to the fidelity with which Greenwich methods were imitated. Dr. Maskelyne, who held the post of Astronomer Royal during forty-six years (from 1765 to 1811), was no unworthy successor to the eminent men who had gone before him. His foundation of the _Nautical Almanac_ (in 1767) alone constitutes a valid title to fame; he introduced at the Observatory the important innovation of the systematic publication of results; and the careful and prolonged series of observations executed by him formed the basis of the improved theories, and corrected tables of the celestial movements, which were rapidly being brought to completion abroad. His catalogue of thirty-six "fundamental" stars was besides excellent in its way, and most serviceable. Yet he was devoid of Bradley's instinct for divining the needs of the future. He was fitted rather to continue a tradition than to found a school. The old ways were dear to him; and, indefatigable as he was, a definite purpose was wanting to compel him, by its exigencies, along the path of progress. Thus, for almost fifty years after Bradley's death, the acquisition of a small achromatic[59] was the only notable change made in the instrumental equipment of the Observatory. The transit, the zenith sector, and the mural quadrant, with which Bradley had done his incomparable work, retained their places long after they had become deteriorated by time and obsolete by the progress of invention; and it was not until the very close of his career that Maskelyne, compelled by Pond's detection of serious errors, ordered a Troughton's circle, which he did not live to employ.