cal science. He was a person of most engaging manners and ap-
pearance and of most amiable character; and his body was followed
to the grave, with every manifestation of respect and affectionate at-
tachment, by the whole body of the pupils and professors of the
institution of which he had so long been a principal ornament.
Dr. William Ritchie was originally Rector of the Royal Academy of Tain in Inverness-shire, where he contrived, by extreme frugality, to save a sufficient sum from his very small annual stipend to attend a course of the lectures of Thenard, Gay-Lussac, and Biot at Paris, and also to provide a substitute for the performance of his duties during his temporary absence from Scotland. His skill and ori ginality in devising and performing experiments with the most simple materials, in illustration of various disputed points of natural phi losophy, attracted the attention of the distinguished philosophers whose occasional pupil he had become: he had also communicated, through Sir John Herschel, who took a strong interest in his for- tunes, to the Royal Society, papers "On a new Photometer," On a new form of the Differential Thermometer," and On the Permea- bility of transparent Screens of extreme tenuity by Radiant Heat," which led to his appointment, through the recomnendation of Major Sabine, to the Professorship of Natural Philosophy at the Royal In- stitution, where he delivered a course of probationary lectures in the spring of 1829: he became, from this time, a permanent resident in London, and was appointed to the Professorship of Natural Philo- sophy at the London University in 1832. He subsequently commu nicated to the Royal Society, papers "On the Elasticity of Threads of Glass, and the application of this property to Torsion Balances ;" and also various experimental researches on the electric and che- mical theories of galvanism, on electro-magnetism and voltaic elec- tricity, which are more remarkable for the practical ingenuity mani- fested in the contrivance and execution of the experiments, than for tlhe influence of the views which they display on the progress of their theory, which was so fully and so happily developed by the cotem- porary labours of another illustrious chemist and philosopher. Dr. Ritchie was subsequently engaged in experiments, on an exten- sive scale, on the manufacture of glass for optical purposes, for the examination of the results of which a Commission was appointed by the Government, with a view to their further prosecution by a public grant of money, or by affording increased facilities of experiment by a relaxation of the regulations of the Excise. A telescope of 8 inches aperture was made by Mr. Dollond from Dr. Ritchie's glass, at the recommendation of this commission; but it is generally understood that its performance was not so satisfactory as to sanction a further expenditure in the extension of these experiments. Dr. Ritchie died in the autumn of the present year, of a fever caught in Scotland; and though the traces of an imperfect and irregular education are but too manifest in most of his theoretical researches, yet he must always be regarded as an experimenter of great ingenuity and merit, and as a remarkable example of the acquisition of a very extensive knowledge of philosophy under difficulties and privations
