Towards the close of the year 1828, Wollaston became dangerously ill with disease of the brain. Feeling his end approaching, and being unable to write himself, he employed an amanuensis to write accounts of such of his discoveries and inventions as he was unwilling should perish with him; and in this manner some of his most important papers were communicated to the Royal Society. It is a curious fact, that, in spite of the extensive cerebral disease under which he laboured, his faculties continued unclouded to the very last. When almost at the point of death, one of his friends having observed, loud enough for him to hear, that he was unconscious of what was passing around him, Wollaston made a sign for pencil and paper, and then wrote down some figures, and after casting up the sum, returned the paper: the amount was found to be correct. Dr. Wollaston died on the 22nd of December, 1828, at the age of sixty-two--only a few months before his great scientific contemporaries, Sir Humphry Davy and Dr. Thomas Young. He was buried in Chiselhurst churchyard, Kent. Dr. William Henry[48] gives the following summary of his character:-- "Dr. Wollaston was endowed with bodily senses of extraordinary acuteness and accuracy, and with great general vigour of understanding. Trained in the discipline of the exact sciences, he had acquired a powerful command over his attention, and had habituated himself to the most rigid correctness both of thought and language. He was sufficiently provided with the resources of the mathematics, to be enabled to pursue with success profound enquiries in mechanical and optical philosophy, the results of which enabled him to unfold the causes of phenomena not before understood, and to enrich the arts connected with those sciences by the invention of ingenious and valuable instruments. In chemistry he was distinguished by the extreme nicety and delicacy of his observations, by the quickness and precision with which he marked resemblances and discriminated differences, the sagacity with which he devised experiments and anticipated their results, and the skill with which he executed the analysis of fragments of new substances, often so minute as to be scarcely perceptible by ordinary eyes. He was remarkable, too, for the caution with which he advanced from facts to general conclusions; a caution which, if it sometimes prevented him from reaching at once the most sublime truths, yet rendered every step of his ascent a secure station, from which it was easy to rise to higher and more enlarged inductions."--_Weld's History of the Royal Society, with Memoirs of the Presidents._ London, 1848.--_Sketches of the Royal Society, &c., by Sir John Barrow, Bart., F.R.S._ London, 1849. THOMAS YOUNG, M.D., F.R.S., &c. MEMBER OF THE INSTITUTE OF FRANCE. Born June 13, 1773. Died May 10, 1829.