space gave him, while yet a boy, almost supernatural power of vision with the naked eye. As a watchmaker's apprentice, he could not command the aid of instruments, but, with the faith of genius, he believed that he would not be denied a sight of nature's secrets, if he made good use of the advantages within his reach. He employed various arts to increase the sensitiveness of his retina, such as looking into dark wells, so that his eye acquired such keenness of vision, that he was the first on the American continent to discover the great comet of 1811. Little did the young apprentice think that he was, in this way, most effectually qualifying himself for the management, as head of an observatory, of some of the finest instruments in the world. His finely trained eye enabled him, in after-life, to make the independent discovery of the dark ring of Saturn, and of a new satellite belonging to the same system. His early mechanical training enabled him to devise and perfect one of the greatest improvements in observation in modern times—viz., the substitution, by means of electricity, of touch, instead of hearing, to mark the instant of any astronomical event. To him, also, arc we chiefly indebted for the art of celestial photography, which promises to revolutionise the system of astronomical observations. May we not hope that Donati's comet, in like manner, has aroused the dormant powers of many a young astronomer who
