SAUDERSON (Dr Nicholas), an illustrious professor of mathematics in the university of Cambridge, and a fellow of the royal society, was born at Threlston in Yorkshire in 1682. When he was twelve months old, he lost not only his eye-sight, but his very eye-balls, by the small-pox; so that he could retain no more ideas of vision than if he had been born blind. His father, who was in the excise, instructed him in numbers; for which he discovered so uncommon a capacity, that with no more learning than he gained at a private academy, and his own industry, assisted by a mere reader, it was resolved to send him to Cambridge not as a scholar but as a master. He accordingly went thither in 1707, and his fame in a short time filled the university. The Principia Mathematica, Optics, and Arithmetica Universalis, of Sir Isaac Newton, were the foundations of his lectures, and afforded him a noble field for the display of his genius; and great numbers came to hear a blind man give lectures on optics, discourse on the nature of light and colours, explain the theory of vision, the effect of glasses
Saunderson, glasses, the phenomenon of the rainbow, and other objects of sight. See the article BLIND, n° 12. 37.
As he instructed youth in the principles of the Newtonian philosophy, he soon became acquainted with its incomparable author, who had several years before left the university; and frequently conversed with him on the most difficult parts of his works: he also lived in friendship with the other eminent mathematicians of the age, Hally, Cotes, De Moivre, &c. Upon Mr Whiston's removal from the professorship, Mr Saunderson's merit was thought so much superior to that of any other competitor, that an extraordinary step was taken to qualify him with a degree; and he was accordingly chosen Mr Whiston's successor in 1711. In 1723, he married the daughter of a clergyman, by whom he had a son and a daughter; and died in 1738. There was scarcely any part of the mathematics on which he had not composed something for the use of his pupils; but he discovered no intention of publishing any thing until by the persuasion of his friends he prepared his Elements of Algebra for the press, which were published by subscription in 2 vols 4to, 1740.
Mr Saunderson had much wit and vivacity in conversation, and was an excellent companion. He had a great regard to truth; and was such an enemy to disguise, that he thought it his duty to speak his thoughts at all times with unrestrained freedom. Hence his sentiments on men and opinions, his friendship or disregard, were expressed without reserve; but his sincerity raised him many enemies. He at first acquired most of his ideas by the sense of feeling; and this, as is commonly the case with the blind, he enjoyed in great perfection. Yet he could not, as some are said to have done, distinguish colours by that sense; for, after having made repeated trials, he used to say, it was pretending to impossibilities. But he could with great nicety and exactness observe the least degree of roughness or defect of polish in a surface. Thus in a set of Roman medals, he distinguished the genuine from the false, though they had been counterfeited with such exactness as to deceive a connoisseur who had judged by the eye. By the sense of feeling also, he distinguished the least variation in the atmosphere; and the author of his life says, that he has been seen in a garden, when observations have been making on the sun, to take notice of every cloud that interrupted the observation almost as justly as they who could see it. He could also tell when any thing was held near his face, or when he passed by a tree at no great distance, merely by the different impulse of the air on his face. His ear was also equally exact. He could readily distinguish the fifth part of a note. By the quickness of this sense he could judge of the size of a room, and of his distance from the wall; and if ever he walked over a pavement, in courts or piazzas which reflected a sound, and was afterwards conducted thither again, he could tell in what part of the walk he stood, merely by the note it sounded. He had naturally a strong healthy constitution; but too sedentary a life brought on a numbness of his limbs, which at last ended in the mortification of one of his feet, of which he died in the 57th year of his age.