Page images

illustrious author. He was also known to Halley, Cotes, Dr. Moore, and many other eminent mathematicians.

Upon the removal of Mr. Whiston from his professorship, Saunderson's merit was thought so much superior to that of any other competitor, that an extraordinary step was taken in his favour, to qualify him as the statutes require. The heads of the University applied to their Chancellor, the Duke of Somerset, who procured the Royal Mandate to confer on him the degree of A.M; in consequence of which, he as elected Lucasian professor of mathematics in Nov. 1711, Sir Isaac Newton interesting himself much on the occasion. His inauguration speech was composed in classical Latin, and in the style of Cicero, with whose works he had been much conversant. From this time he applied himself closely to the reading of lectures, and gave up his whole time to his pupils. He continued to reside among the gentlemen of Christ's College, till the year 1723, when he took a house in Cambridge. He shortly afterwards married the daughter of the Rev. Mr. Dickens, Rector of Boxworth, in Cambridgeshire, by whom he had a son and a daughter. When George the II. in 1728, visited the University, he requested to see Professor Saunderson. In compliance with this desire, he waited on his Majesty in the Senate House, and was then by the King's command created Doctor of Laws. He was admitted a member of the Royal Society, in 1736.

Dr. Saunderson was naturally of a vigorous aud healthy constitution; but having confined himself to a sedentary life, he at length became scorbutic; in the spring of 1739, he complained of a numbness


in his limbs, which ended in a mortification in his foot, and unfortunately his blood was so vitiated by the scurvy,

that assistance from medicine was not to be expected. When informed that his death was approaching, he remained for a short time calm and silent; but he soon recovered his former vivacity, and conversed with his accustomed ease. He died on the 19th April, 1739, aged 57 years, and was buried at his own request in the chancel of Boxworth.

Dr. Reid, who was an intimate friend of Saunderson, in speaking of his scientific acquirements, observes, “One who never saw the light, may be learned and knowing in every science, even in optics; and may make discoveries in every branch of philosophy. He may

understaud much as another man, not only of the order, distances, and motions of the heavenly bodies, but of the nature of light, and of the laws of the reflection and refraction of its rays. He derstand distinctly how those laws produce the phenomena of the rainbow, the prism, the camera obscura, the magic lantern, and all the powers of the microscope and telescope. This is a fact sufficiently attested by experience."

“ Dr. Saunderson understood the projection of the sphere, and the common rules of perspective, and if he did, he must have understood all that I have mentioned. If there were any doubt of Dr. Saunderson's understanding these things, I could mention having heard him say in conversation, that he found great difficulty in understanding Dr. Halley's demonstration of that proposition,—that the angles made by the circles of the sphere, are equal to the angles made by

may un

their representatives in the stereographic projection. ‘But,' said he, 'when I laid aside that demonstration, and considered the proposition in my own way, I saw clearly that it must be true. Another gentleman, of undoubted credit and judgment in these matters, who had part in this conversation, remembers it distinctly,”

Saunderson we are told, though blind, could lecture on the prismatic spectrum, and on the theory of the rainbow. It is even conceivable, that by long habits of poetical reading, he might have become capable of producing such a description of their order in the spectrum, as is contained in the following lines of Thomson.*

There was scarcely any part of the science on which he had not composed something; but he discovered no intention of publishing any thing, till, by the persuasion of his friends, he prepared his “Elements of Algebra” for the press; which was published by subscription in two volumes, 4to, 1740.

He left many other writings, though none perhaps prepared for the press; among these were some valuable comments on Newton's Principia, which not only

“ First, the flaming red
Sprung vivid forth; the tawny orange next,
And next delicious yellow, by whose side
Fell the kind beams of all refreshing green;
Then the pure blue that swells autumnal skies,
Ethereal played, and then of sadder hue,
Emerged and deepened indigo, as when
The heavy-skirted evening droops with frost,
While the last gleamings of refracted light,
Died in the fainting violet away."

explain the more difficult parts, but often improve upon the doctrines. These are published in Latin, at the end of his posthumous “ Treatise on Fluxions,” a valuable work, published in 8vo, 1756.

His manuscript Lectures too, on most parts of natural philosophy, might make a considerable volume, and prove an acceptable present to the public, if printed.

Dr. Saunderson, as to his character, was a man of much wit and vivacity in conversation, and esteemed an excellent companion. He was endued with 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; a sincerity which raised him many enemies. A blind man moving in the sphere of a mathematician, seems to be a phenomenon difficult to be accounted for, and has excited the admiration of every age in which it has appeared. Tully mentions it as a thing scarcely credible of his own master in philosophy, Diodotus, that he exercised himself in it with more assiduity after he became blind; and, what he thought next to impossible to be done without sight, that he professed geometry, describing his diagrams so exactly to his scholars, that they could draw every line in its proper direction. But if we consider that the ideas of extended quantity, which are the chief objects of mathematics, may as well be acquired by the sense of touch, as by that of sight; that a fixed and steady attention is the principal qualification for this study, and that the blind are, by necessity, more abstracted than others, (for which reason it is said, that Democritus put out his eyes that he might think more intensely,) we shall perhaps find reason to suppose that there is no branch of science so much adapted to their circumstances. At first, Dr. Saunderson acquired most of his ideas by the sense of touch; 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 impossibilites. But he could with great nicety and exactness perceive the smallest degree of roughness, or defect of polish, on 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 from the eye. By the sense of touch also, he distinguished the least variation; and he has been seen in a garden, when observations were making on the sun, to take notice of every cloud that interrupted the observation, almost as justly as others 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 fourth part of a note by the quickness of this sense; and could judge of the size of a room, and of his distance from the wall. And if he ever walked over a pavement in courts or piazzas which reflected sound, and was afterwards conducted thither again, he could tell in what part of the walk he

« PreviousContinue »