1825 he received from his aunt, Caroline Herschel, a copy of her zone catalogue of nebulæ; in his reply he said, "Those curious objects I shall now take into my especial charge; nobody else can see them." He referred to his being the owner of a 20-foot "front view" reflector constructed by himself with his father's aid in 1820. With this instrument he made a great review of all the nebulæ visible in England, the result being a catalogue of 2307 nebulæ, of which 525 were discovered by himself; presented to the Royal Society in 1833. Herschel also continued the search for double stars, using the larger telescope which belonged to South; he discovered 3346 pairs, and made extensive measurements of known pairs.
For Lardner's Cabinet Cyclopedia he prepared an article on astronomy which was subsequently rewritten and published in 1849 as a book under the title Outlines of Astronomy. This book went through many editions, and was translated into many languages, even the Roman, Chinese and Arabic. For this Cyclopedia Herschel also prepared an introductory volume under the title Preliminary Discourse on the Study of Natural Philosophy. By Natural Philosophy he does not mean Physics only but it includes the experimental and observational sciences, namely, in the order of Herschel's book, Mechanics, Optics, Astronomy, Geology, Mineralogy, Chemistry, Heat, Electricity, Zoology, Botany. Herschel advanced several of these sciences, and had a special knowledge of all, excepting perhaps the two last; he was thus rarely well fitted to write on their logic and methods. The work treats of the methods of scientific research since the time of Francis Bacon. On the title page is a picture of Bacon and the words Naturæ minister et interpres taken from his first aphorism; (these words, as all in this audience know, are also in the motto of Lehigh University). In it will be found many of the philosophic ideas which were elaborated by the British mathematicians whose lives we have discussed. Here we find the idea, afterwards elaborated by Clerk Maxwell, that the atoms of the chemist bear the characters of "manufactured articles"; here we find the thought, elaborated by Tait in verse, that Nature presents to us in a confused and
