In 1827 Faraday's first book--_On Chemical Manipulation_--was produced. Faraday had published a short while before an account of some discovery he had made with respect to the existence of fluid sulphurs; in this year he writes:--"I have just learned that Signor Bellani had observed the same fact in 1813. M. Bellani complains of the manner in which facts and theories which have been published by him are afterwards given by others as new discoveries; and though I find myself classed with Gay-Lussac, Sir H. Davy, Daniell and Bostock, in having thus erred, I shall not rest satisfied without making restitution, for M. Bellani in this instance certainly deserves it at my hand." This is worthy of note as a slight illustration of the true integrity of Faraday's character; much as he valued any original discovery he might make, he valued much more that absolute truth which made him render honour to any predecessor even at his own expense; this was done, too, always as a matter of course, without the slightest spirit of grudging. His behaviour on such occasions, which are indeed too trying to most persons, had perhaps a great deal to do with the feeling which he awakened in all who came in contact with him. Never, perhaps, was there a more unselfish, as there was never a more universally beloved, man. "His friendship," as Professor Tyndall says, "was energy and inspiration." Faraday was appointed member of a "committee for the improvement of glass for optical purposes;" one of the results of his investigation was that when delivering, in 1829, the Bakerian lecture at the Royal Institution, he took for his subject, "The Manufacture of Glass for Optical Purposes." For further investigation of this subject a special experimenting room and furnace had been built at the Institution in 1827, and a special assistant--Sergeant Anderson--engaged to assist Faraday. One chief object of these experiments was to improve the glasses of telescopes. This desired result was, however, not attained, although some notable work was done; the glass then manufactured, for instance, became invaluable in some of Faraday's later researches. In 1830 the glass-making investigation stopped, and in the year following the committee presented their report to the Royal Society which had appointed them. The recognition of Faraday's importance in the world of science was now made more manifest each year; not only were honours done him by various English and Continental societies, but in 1826 the managers of the Royal Institution "relieved him from his duty as chemical assistant at the lectures because of his occupation in research." In 1829 he was invited to attend the meetings of the managers. In 1827 he had been offered the Professorship of Chemistry in London University, but much as he felt the honour which was done him, Faraday declined it, and from the noblest of motives, as will be seen in this passage from his letter to Dr. Lardner on the subject.