PHYSICS OF THE NINETEENTH CENTURY.- LIGHT. 445 



quirements than Young. Look over a list of his writings, and you 

 will see medicine and engineering, mathematics and fine art, astro- 

 nomy and philology, mechanics and zoology, represented by turns. 

 Though he was brought up as a member of the Society of Friends, 

 and though his acquisitions would have been supposed compatible 

 only with the life of a retired student, he was, on the contrary, a man 

 of the world, witty, elegant in manners, arid mixing in the best society 

 of the capital. He was well versed in the fine arts ; there was scarcely 

 a musical instrument which he could not play; and he acquired a 

 competent knowledge of painting. His discovery of the key to. the 

 mysterious Egyptian hieroglyphics, whose interpretation had baffled 

 the learned for so many ages, added greatly to his fame. It may 

 appear singular that a man of Young's extraordinary intellectual power 

 should have achieved but a very indifferent success in the practice of 

 medicine, which was the career he had originally chosen. Perhaps it 

 was the amount of his knowledge which made him less confident in pre- 

 scribing medicines of which he could not calculate all the effects, for the 

 tendency of his mind was essentially towards the study of truths admit- 

 ting of deductive demonstration. In 1818, when he was appointed 

 Secretary to the Board of Longitude, he relinquished the practice of 

 medicine altogether, and devoted himself to the superintendence of 

 the " Nautical Almanac," while the " Journal of the Royal Institution" 

 gave evidence of his capabilities of dealing with the most difficult pro- 

 blems of astronomy and navigation. Young died in 1829 at the age 

 of fifty-six. 



It was in the " Bakerian Lecture " before the Royal Society in 1800 

 that Young, in announcing that the more recent observations made 

 by himself and others had induced him to revert to his former opinion, 

 noticed also other interesting particulars relating to the " mechanism 

 of the eye." The records of the many observations and discoveries 

 made from time to time concerning the eye constitute of themselves 

 quite an extensive literature. Indeed, the extent of the bibliography 

 of this one subject would certainly astonish a reader unversed in 

 scientific inquiries. The human eye has been studied in many different 

 relations anatomical, physiological, optical, medical, and psycho- 

 logical, and the results form a series of discoveries of the highest in- 

 terest and beauty. Our knowledge of the eye, however, unlike many 

 of the great epoch-marking discoveries in science, cannot be referred 

 especially to any individual investigation. It has been a growth, 

 and the result of the general advancement in the several branches 

 of sciences, and of the researches made by a host of inquirers, espe- 

 cially during the seventeenth, eighteenth, and nineteenth centuries. 

 Young's contributions to the theory of vision, which were laid before 

 the Royal Society in the Bakerian Lecture for 1800, were important 

 additions to our knowledge of the subject ; and though these researches 

 form by no means the chief title of Young to scientific fame, a. few 



