versed in Greek, Latin, French, Italian, Hebrew, Persic, and Arabic, and in forming the characters of these languages had already acquired a considerable portion of that beauty and accuracy of penmanship which was afterwards so remarkable in his copies of Greek compositions, as well as those subjects connected with the literature of ancient Egypt. A story is related of him, that when requested a few years later, by a friend of Dr. Brocklesby, who presumed somewhat upon Young's youthful appearance, to exhibit a specimen of his penmanship, he replied by writing a sentence in his best style in fourteen different languages.

In 1787 Young was engaged, in conjunction with Mr. Hodgkin, as private tutor to Hudson Gurney, grandson of Mr. David Barclay, of Youngsbury, near Ware, in Hertfordshire, and he remained thus occupied during the space of five years, extending his knowledge as far as possible. The number of books he read through at that time was comparatively small, but whatever book he began to read, he read completely and deliberately through, and it was perhaps this determination always to master what he might happen to be engaged on before attempting anything else, which enabled Dr. Young to attain so great knowledge on such various subjects. He himself had little faith in any peculiar aptitude being implanted by nature for any given pursuits. His favourite maxim was, that whatever one man had done another might do, and that the original difference between human intellects was much less than it was supposed to be; in this respect he resembled his great predecessor Newton, and his cotemporary Dalton, both of whom had unbounded confidence in the powers of patient thought.

In the autumn of 1792 Thomas Young removed to London, in order to study medicine, which profession he had determined to adopt, being greatly influenced in his choice by the wishes of his uncle Dr. Brocklesby. This gentleman had kindly undertaken the charge of his education, and Young was by him introduced to the members of the most distinguished literary circles in the metropolis, including Burke, Drs. Lawrence and Vincent, Sir Joshua Reynolds, Sir George Baker, and others. In the autumn of 1793 he became a pupil at St. Bartholomew's Hospital, and in October 1794 proceeded to Edinburgh, still further to prosecute his medical studies. While residing at Edinburgh Dr. Young mixed largely in society, began the study of music, took lessons on the flute, and also private lessons in dancing, and frequently attended performances at the theatre. From this period he gave up the external characteristics of the Quakers, and ultimately ceased to belong to their body, although hẹ practised to the end of his life the general simplicity of their moral conduct.

During the year 1795 he commenced a tour on the Continent, staying at the University of Gottingen during nine months, in order to prosecute his studies and take a doctor's degree. In February,

1797, he came back to England, and was almost immediately after his return admitted a Fellow-Commoner of Emmanuel College, Cambridge; the Master of the College, Dr. Farmer, saying as he introduced Young to the fellows, "I have brought you a pupil qualified to read lectures to his tutors."

In December 1797 Young's uncle, Dr. Brocklesby, died, bequeathing to his nephew the sum of 10,000l., besides his house, furniture, and a choice collection of pictures. Dr. Young was now entirely at liberty to form his own scheme of life, and he determined to commence practice as a physician, for which purpose, after having completed his terms of residence at Cambridge, he took a house in Welbeck Street (No. 48), which he continued to occupy for fiveand-twenty years. His practice as a physician, although respectable, was never large. He wanted that confidence or assurance which is so necessary to the successful exercise of the profession. He was perhaps too deeply informed, and therefore too sensible of the difficulty of arriving at true knowledge in the science of medicine ever to form a hasty judgment; while his great love of, and adherence to truth, made him often hesitate where others would have felt no difficulty in expressing an opinion. It was perhaps a happy circumstance for the fame of Dr. Young that this should be the case, as he was thereby enabled to devote a considerable portion of his time to those literary and scientific studies in which so few could compete with him. In 1799 he published his memoir entitled 'Outlines and Experiments respecting Sound and Light,' which was read before the Royal Society and printed in their 'Transactions.' Other papers, 'On the Theory of Light and Colours,' followed, which the council of the Royal Society selected for the Bakerian lectures. In the year 1801 Dr. Young accepted the office of Professor of Natural Philosophy at the Royal Institution, which had been established the year previously. The conducting of the journal of the Institution was also entrusted to his care, in conjunction with his colleague Sir Humphry Davy, at that time Professor of Chemistry. Dr. Young remained at the Royal Institution two years, during which period he gave a course of lectures on 'Natural and Experimental Philosophy,' a syllabus of which he published in 1802, announcing for the first time his great discovery of the general law of the interference of the undulations of light. His lectures were not, however, popular; they embodied too much knowledge to be intelligible to any considerable portion of his hearers; and the matter was so abundant and the style so condensed, that students tolerably versed in science might have found it extremely difficult to follow him in his masterly discussions.

Dr. Young had been elected a Fellow of the Royal Society as early as the year 1794, when he had just completed his twenty-first year; he was now appointed (1802) Foreign Secretary to the same Society, an office which he held during the remainder of his life,

and for which he was well qualified by his knowledge of the principal languages of Europe.

In 1804 he married Eliza, the daughter of James Primrose Maxwell, of Cavendish Square, and this union is said to have been attended with uninterrupted happiness; his wife who survived him left no children.

In 1807 appeared his most elaborate and valuable work, 'A Course of Lectures on Natural Philosophy and the Mechanical Arts,' being the embodiment of the sixty lectures delivered while at the Royal Institution, together with the labour of three more years occupied in further arranging and improving them. This work comprises a complete system of natural and mechanical philosophy, drawn from original sources, and is distinguished not only by the extent of its learning and the accuracy of its statements, but by the beauty and originality of the theoretical principles. It also contains a disquisition upon the doctrine of interference in the undulatory theory of light mentioned before, the general law of which he thus enunciates: "When two undulations from different origins coincide, either perfectly or very nearly in direction, their joint effect is a combination of the motions belonging to each."* Šir John Herschel, speaking of this discovery, says that it alone "would have sufficed to have placed its author in the highest rank of scientific immortality, even were his other almost innumerable claims to such a distinction disregarded." Amongst other laborious and difficult matters of investigation, Dr. Young made the first and most important steps in reading the Egyptian Hieroglyphics, in which he preceded Champollion; and he afterwards, in 1823, published a work on this subject, under the title of 'An Account of some recent Discoveries in Hieroglyphical Literature and Egyptian Antiquities; including the author's original Alphabet as extended by Mr. Champollion; with a Translation of five unpublished Greek and Egyptian Manuscripts.' In the year 1808 Dr. Young was admitted a fellow of the College of Physicians, and in 1810 was elected physician to St. George's Hospital, a situation which he retained for the remainder of his life. In 1813 he published 'An Introduction to Medical Literature, including a system of practical Nosology intended as a guide to Students and as an Assistant to Practitioners.' In 1816 Dr. Young was appointed Secretary to the Commission empowered to ascertain the length of the second's pendulum, and thereby establish an uniform system of weights and measures. Two years subsequent to this he became secretary to the Board of Longitude, and on the dissolution of that body, became sole conductor of the Nautical Almanac.' Dr. Young at various times contributed eighteen articles to the 'Quarterly Review,' of which nine were on scientific subjects-the rest on medicine, languages, and criticism.

*Life of Thomas Young, M.D., &c., by George Peacock, page 143.

Between 1816 and 1823 he wrote sixty-three articles for the Supplement to the Encyclopædia Britannica,' Sixth Edition, of which forty-six were biographical. In the year 1821 he made a short tour in Italy with his wife, and, in August 1827, was elected one of the eight Foreign associates of the Academy of Sciences at Paris, in the place of Volta, who died in 1826; the other competitors for this honour being the astronomers Bessel and Olbers, Brown the botanist, Blumenback, Leopold, Von Buch, Dalton, and Plana the mathematician.

Dr. Young's course of life, considered apart from the variety of his occupations, was remarkably uniform. He resided in London from November to June, and at Worthing from July to the end of October, continuing this regular change of residence for fourteen successive years. In the year 1826 he removed from his house in Welbeck Street, where he had resided for a quarter of a century, to another in Park Square, which had been built under his own directions, and fitted up with great elegance and taste. He continued to live here for the remainder of his life. During the month of February, 1829, he began to suffer from what he considered repeated attacks of asthma. His health gradually got worse, but though thus under the pressure of severe illness, nothing could be more striking than the entire calmness and composure of his mind, or could surpass the kindness of his affections to all around him. In the very last stage of his complaint, in an interview with Mr. Gurney, his perfect self-possession was displayed in the most remarkable manner. After some information concerning his affairs, and some instructions concerning the hieroglyphical papers in his hands, he said, that perfectly aware of his situation, he had taken the sacrament of the Church on the day preceding; that whether he should ever partially recover, or whether he were rapidly taken off, he could patiently and contentedly await the issue. His illness continued, with some slight variations, until the morning of the 10th of May, when he expired without a struggle, having hardly completed his fifty-sixth year. The disease proved to be an ossification of the aorta, the large arterial trunk proceeding from the left ventricle of the heart. It must have been in progress for many years, and every appearance indicated an advance of age, not brought on probably by the natural course of time, nor even by constitutional formation, but by unwearied and incessant labour of mind from the earliest days of infancy. His remains were deposited in the vault of his wife's family, in the church of Farnborough, in Kent.-Life of Thomas Young, M.D., &c., by Dr. George Peacock, Dean of Ely. London, 1855.-Memoir by Dr. D. Irving, Encyclopædia Britannica, Eighth Edition.-English Cyclopædia. London, 1858.

APPENDIX.

JOSEPH BLACK, M.D.

PROFESSOR OF THE UNIVERSITIES OF EDINBURGH AND GLASGOW.

Born 1728.* Died November 26, 1799.

Dr. Joseph Black was born at Bourdeaux, where his father, a native of Belfast but of Scotch descent, was settled as a wine merchant; and being a man of engaging disposition and extensive information was much esteemed by his friends, among whom he reckoned Montesquieu, at that time one of the presidents of the court of justice in the province where Mr. Black resided. At the age of twelve Joseph Black was sent to a school at Belfast, where he remained for some years. In 1746 he was removed to the College at Glasgow and ever afterwards lived in Scotland, which was, properly speaking, his native country. While at the College of Glasgow he studied under the celebrated Dr. Cullen, then professor of anatomy and lecturer on chemistry, and in the year 1751 removed to Edinburgh to complete the course of his medical studies. In the following year Black made his first great discovery of the cause of the causticity of lime, a property till then supposed to be due to the absorption by the lime of some igneous agency. He placed this question on a scientific basis by ascertaining the chemical difference between quick-lime and other forms of the carbonate, and first announced his discovery in a Latin Thesis upon the occasion of his taking his degree of Doctor of Medicine in 1754. It was not, however, given in its fullest details until the year afterwards, when he published his celebrated work entitled, Experiments on Magnesia, Quick-lime, and other alkaline substances; a work which Lord Brougham describes as being incontestably the most beautiful example of strict_inductive investigation since the 'Optics' of Sir Isaac Newton. In 1754, as has been mentioned, Black took his medical degree at Edinburgh; in 1756 he was appointed to succeed Dr. Cullen as professor of anatomy and lecturer on chemistry in the University of Glasgow. Soon after, however, he exchanged this for the professorship of medicine at the same university, as being more congenial to his tastes. Dr. Black continued at the University of

*Lord Brougham gives the date of Dr. Black's birth as 1721.-Lives of Philosophers. Third Edition, 1855.