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PROFESSOR DE MORGAN was born at Madura, in Southern India, in June, 1806. Several members of his father's family had distinguished themselves in the Indian army. His great-grand-father and grandfather had fought under Warren Hastings, and his father, Colonel John De Morgan, was a man of considerable energy. But it was from the maternal side that he must have inherited his mathematical powers. His mother was a grand daughter of James Dodson, F.R.S., author of the Anti-logarithmie Canon, a pupil and friend of De Moivre's, and master of the Mathematical School of Christ's Hospital; he was also the chief founder of the Equitable Life Assurance Company, for which he calculated the first tables.
In August, 1806, Colonel De Morgan and his wife returned to England, bringing with them a daughter, and their infant son, Augustus, then three months old. He had been born with but one eye, but was a strong child. On arriving in England, they first settled at Worcester, and then lived rather a migratory life, moving from place to place in the west of England. When the Professor was between four and five, he remembered his father giving him his first lessons in arithmetic. After a few years Colonel De Morgan returned to India, again leaving his wife and children in this country. And while on his way to England in 1816, he was taken ill and died at sea off St. Helena, leaving his widow with four children. The little Augustus was then a boy of ten, and passed from one private school to another, being crammed with general knowledge, Latin, Greek, and even Hebrew, before he was fourteen. In after life he had a strong aversion to the overstrained education of young children; he hated cramming, and the competitive examinations of the present day, believing them to be an almost unmixed evil, against which, however, it was in vain to remonstrate the errors which he deplored would only become apparent by their fatal results in the next genera-tion. At the age of sixteen and a half he passed on to Cambridge, where he entered at Trinity College. His rooms were in the south-east corner of the Great Court, then called "Mutton Hole Corner," which he used to affirm was a corruption of Merton Hall Corner. Here he spent his undergraduateship, and greatly developed his love for mathematics, which had already begun to show itself before he left school. He, however, indulged his musical tastes, learning to play the flute, of which he is said to have been one of the best amateur players in England, and also spending much of his time in general reading, which greatly interfered with his study for honours. One of his college lec-turers was Mr. Airy, who had been senior wrangler of the year in which the young De Morgan entered.
He had not completed his twenty-first year when he gained the fourth place in the mathematical tripos of 1827, the order of the list being Gordon, Turner, Cleasby, De Morgan. The place of the youthful wrangler, though it failed to declare his real power or the exceptional aptitude of his mind for mathematical study, would, however, have been sufficient to have secured for him a fellowship, and he, no doubt, would have found a congenial field of labour within the walls of his university, if his conscientious scruples had not prevented his signing the tests which at that time were required from those who took up their degree of M.A. as well as from all Fellows of Colleges.
In his later years he termed himself with characteristic pleasantry, "A Christian Unattached," and the considerations which caused him to describe thus negatively his religious position were so far operative on his conscience in early manhood, that he forbore to secure a high wrangler's ordinary share of Univer-sity preferment by formal, and what would have been, to him, insincere subscription.
In 1863 he wrote, "What is belief? A state of the mind. What is it often taken to be? An act of the mind. The imperative future tense -- I will believe thou shalt believe, &c. -- which has no existence except in the grammar-book, represents a futile attempt which people make upon themselves and upon others." This sentiment, expressed so forcibly in his later life, was the moving power which, when he was on the threshold of manhood, caused him to withdraw from the University in which he would, doubtless, have become a powerful leader of mathematical thought, had his religious feelings been less acute or his principles more elastic.
On coming to London, he entered at Lincoln's Inn, and would have been compelled to forsake mathematics for the study of the law, but that, in 1828, the University of London, now University College, was founded, and he was appointed to the mathematical chair. In May of the same year he became a Fellow of this Society, and in the following November gave his first introductory lecture at University College. In his own words, he then "began to teach himself to better purpose than he had been taught, as does every man who is not a fool, when he begins to teach others, let his former teachers have been what they may."
In 1837, ten years after his appointment at University College. he married Sophia Elizabeth, the daughter of Mr. William Frend, formerly a Fellow of Jesus College, Cambridge, author of several mathematical books, and Actuary of the Rock Life Assurance Office. The professional experiences of his father-in-law opened to De Morgan a fresh sphere of labour, in which he turned his mathematical acquirements to account in the service of many of the London Insurance Companies. In this new field of labour he might, doubtless, have made a much larger income than he could ever hope to derive from his professorship at University College, but he was devotedly attached to the principles of the new institution, and made it his first duty to advance its interests.
He was so punctual and so regular in the performance of his college duties that his passage to and from his classes served as a time-piece to observant students. Soon after eight o'clock every morning he might have been seen passing along the railed enclosure of University College, so absorbed in thought that his nearest friends might pass him without being recognised.
He remained a firm supporter of the institution and its principle of no religious tests till the year 1866, when the Council, in making an appointment to the chair of Logic and Mental Philosophy, refused, as the Professor believed, one of the candidates on account of his religious opinions. Professor De Morgan, acting under the conviction that the Institution to which he had devoted the best years of his life, was forsaking the leading principle on which it had been founded-a principle which from early manhood had influenced him, and was now dearer to him than ever felt it his duty to resign his professorship.
And thus, though deeply disappointed and grieved at the step he felt forced to take, Professor De Morgan, who had for nearly forty years been the chief honour and ornament of University College, left it, and, we are informed, never afterwards entered its gates.
To estimate the energy of the Professor, we must look at him not only as a teacher of mathematics, but as a mathematician, an actuary, a logician, an historian, a biographer, and a bibliophile.
First, then, as a teacher of mathematics; perhaps no man has been more successful in training distinguished mathematicians, amongst whom we may mention the names of Professor Clifton, Judge Hargreave, Mr. Routh, and Mr. Todhunter. Professor Sylvester also attended his lectures, though the relationship of professor and pupil did not in this case last very long. He had a method of interesting his hearers in the subjects on which he lectured, and of making them love mathematics for its own sake, to which few other men have ever attained. He devoted more time and labour to the logical processes by which the various rules are demonstrated than to the more technical parts of his subject, though of these too, in their proper place, Professor De Morgan was never unmindful, spending the greatest care on teaching the art of rapid and accurate computation.
His exposition of the elementary principles of the Differential Calculus, and of the logical processes of his Double Algebra, was most masterly and exhaustive, and was often enlivened by such humorous illustration that it never failed to impress itself upon the minds of his hearers. The subject matter of every lecture which he delivered was entered by him in a note-book, and was sent into the library of the college for the benefit of his pupils while writing out and expanding their own notes.
As a mathematician his work was so various that it would be difficult for any one man to review it; but we may allude, in passing, to his double algebra, which was certainly the forerunner of Quaternions, and contained the complete geometrical inter-pretation of the √-1. Sir William Rowan Hamilton, in the Preface to his Lectures on Quaternions, at p. 41, says: "But I wish to mention that, among the circumstances which assisted to prevent me from losing sight of the general subjects, and from wholly abandoning the attempt to turn to some useful account those early speculations of mine on triplets and on sets, was probably the publication of Prof. De Morgan's first paper on the Foundation of Algebra, of which he sent me a copy in 1841." And at p. 64 of the same Preface he says, in speaking of this theory of Sets of which he considered Quaternions (in their symbolical aspect) to be merely a particular case, "Before the publication of those sets, the closely connected conception of an 'algebra of the nth character' had occurred to Prof. De Morgan in 1844, avowedly as a suggestion from the Quaternions.' A great portion of his original investigations will be found in the form of communications to the Transactions of the Cambridge Philosophical Society."
As a writer of mathematical text-books he took the highest rank, his books being more suitable, however, for teachers than for pupils. They were characterised by extreme clearness, ex-haustiveness, and suggestiveness. Perhaps those best known are his Elements of Arithmetic, published 1830; his Elements of Algebra, published 1835; and his Differential and Integral Calculus, with Elementary Illustrations, which is a perfect mine of original thought, and in which some of the most important extensions which the subject has since received are distinctly foreshadowed. It was published by the Society for the Diffusion of Useful Knowledge.
His first mathematical text-book was a Translation of the Elements of Algebra by Bourdon, published when he was only twenty-two years of age. He wrote text-books upon trigonometry, double algebra, the theory of probabilities, connexion of number and magnitude, projection, and the use of the globes; besides which he edited more than one table of logarithms, and wrote prefaces and notes to the books of other mathematical authors. The list of his works and their various editions occu-pies nine pages of the British Museum Catalogue.
As an actuary he occupied the first place, though he was not directly associated with any particular office; but his opinion was sought for by professional actuaries on all sides, on the more difficult questions connected with the theory of probabilities, as applied to life-contingencies. In 1830 he wrote for the Cabinet Cyclopædia his "Essay on Probabilities," -- a book which still retains a high place among the literature of insurance offices.
As a logician he was well known, and his Formal Logic, together with the treatise of Dr. Boole, may be said to have created a new era in logical science. His controversy with Sir William Hamilton will long be remembered.
As an historian and biographer the English Encyclopædia says of him, that "he had a great affection for, and an extensive and minute erudition in, all kinds of literary history, biography, and antiquities." He was one of the most extensive contributors to the Penny Cyclopædia, many of the articles of scientific biography having been written by him, as well as most of the mathematical and astronomical articles. His contributions to the work are said to amount to one-sixth of the whole Cyclopædia. The lives of Newton and Halley, in Knight's British Worthies, were also from his pen. Besides these he published an index of the correspondence of the scientific men of the seventeenth century; and a book entitled General Information on Subjects of Chro-nology, Geography, Statistics, &c., References for the History of the Mathematical Sciences, 1842.
As a bibliophile, his Arithmetical Books from the Inven-tion of Printing to the present time, 1847, and his Budget of Paradoxes, will long remain celebrated. A reprint of the latter, greatly enlarged from manuscript notes left by the Professor, is now being taken through the press by his widow. He was the possessor of a very choice collection of mathematical works, which have, since his death, been purchased by Lord Overstone, and presented to the University of London, where they now form a De Morgan Library; most of the volumes contain bibliographical notes and sometimes quaint and humorous scraps from newspapers or other books pasted into their covers.
He was a true bibliophile, and revelled in all the mysteries of watermarks, title-pages, colophons, catchwords, and the like. He wrote in the preface-dedicatory of his list of arithmetical books, "The most worthless book of a bygone day, is a record worthy of preservation. Like a telescopic star, its obscurity may render it unavailable for most purposes; but it serves, in hands which know how to use it, to determine the places of more important bodies."
In addition to this, the Professor contributed largely to the Philosophical Magazine, the North British Review, the Athenaeum, the Companion to the Almanac, and Notes and Queries. The Athenæum says of him, that if all the articles which he contributed to literary and scientific journals were col-lected together, there would be found such a mass of literary achievement as seldom comes from the pen of a man whose sole business is to write for journals. He also compiled a Book of Almanacs, with an index of reference, by which the almanac may be found for every year up to A.D. 2000, with means of finding the day of the new moon from B.C. 2000 to A.D. 2000, published 1851.
The Professor also devoted much of his time to the business of this Society. For a period of more than thirty years he was officially connected with it, sometimes serving upon the Council, sometimes as Vice-President, and for many years as Secretary, in conjunction with Mr. Bishop and Admiral Manners, and dur-ing this period many of the volumes of the Monthly Notices were produced under his editorship.
He was the first President, and took great interest in the formation of the London Mathematical Society, of which his son, the late George Campbell De Morgan, was one of the first honorary secretaries. Soon after the untimely death of this son, who was a mathematician of considerable promise, he wrote to one of the early officers of the Mathematical Society, "My son's loss has thrown much grief over my house, but no gloom. He is spoken of as if he were removed to be followed in time, and to be kept in memory all the more, because he is no longer to remind us of himself by his direct presence. ... I make out distinctly, from written evidence among his papers, that you and he were the projectors of the Mathematical Society ... and I wish to have the evidence of this very distinctly preserved. There is quite enough in my hands to establish the fact, but I should be glad of every detail that you can remember."
A very inadequate notion of Professor De Morgan will be formed by those who look only at his works. From them, indeed, it will be seen that he was a reader who relished every kind of intellectual food, and a thinker whose subtlety was only surpassed by his originality. They abound also with proof that he overflowed with humour; but his familiar associates alone can render justice to the versatility of his powers and the sweet-ness of his disposition.
Knowing many subjects thoroughly, there was scarcely one about which he did not know much. He passed, for diversion's sake, from one arduous study to another, but though he found a pastime in intellectual efforts that would exhaust ordinary students, he did not disdain literature that pedants are apt to contemn as frivolous. He was an habitual and eager reader of novels, especially humorous novels, but there were times when, in the absence of a good novel, he could enjoy a bad one. The paradoxers, whom he infuriated by his banter, were strangely at fault when they accused him of malignity. He was the kindliest, as well as the most learned, of men -- benignant to every one who approached him, never forgetting the claims which weakness has on strength. Soon after the death of his son the Professor was attacked with a disease of the kidneys, which during more than two years of distressing illness reduced him to a shadow of his former self; and on Saturday, the 18th of March, 1871, at one o'clock in the afternoon, his spirit was released from the body, which had long been only a burden to it.
In August, 1806, Colonel De Morgan and his wife returned to England, bringing with them a daughter, and their infant son, Augustus, then three months old. He had been born with but one eye, but was a strong child. On arriving in England, they first settled at Worcester, and then lived rather a migratory life, moving from place to place in the west of England. When the Professor was between four and five, he remembered his father giving him his first lessons in arithmetic. After a few years Colonel De Morgan returned to India, again leaving his wife and children in this country. And while on his way to England in 1816, he was taken ill and died at sea off St. Helena, leaving his widow with four children. The little Augustus was then a boy of ten, and passed from one private school to another, being crammed with general knowledge, Latin, Greek, and even Hebrew, before he was fourteen. In after life he had a strong aversion to the overstrained education of young children; he hated cramming, and the competitive examinations of the present day, believing them to be an almost unmixed evil, against which, however, it was in vain to remonstrate the errors which he deplored would only become apparent by their fatal results in the next genera-tion. At the age of sixteen and a half he passed on to Cambridge, where he entered at Trinity College. His rooms were in the south-east corner of the Great Court, then called "Mutton Hole Corner," which he used to affirm was a corruption of Merton Hall Corner. Here he spent his undergraduateship, and greatly developed his love for mathematics, which had already begun to show itself before he left school. He, however, indulged his musical tastes, learning to play the flute, of which he is said to have been one of the best amateur players in England, and also spending much of his time in general reading, which greatly interfered with his study for honours. One of his college lec-turers was Mr. Airy, who had been senior wrangler of the year in which the young De Morgan entered.
He had not completed his twenty-first year when he gained the fourth place in the mathematical tripos of 1827, the order of the list being Gordon, Turner, Cleasby, De Morgan. The place of the youthful wrangler, though it failed to declare his real power or the exceptional aptitude of his mind for mathematical study, would, however, have been sufficient to have secured for him a fellowship, and he, no doubt, would have found a congenial field of labour within the walls of his university, if his conscientious scruples had not prevented his signing the tests which at that time were required from those who took up their degree of M.A. as well as from all Fellows of Colleges.
In his later years he termed himself with characteristic pleasantry, "A Christian Unattached," and the considerations which caused him to describe thus negatively his religious position were so far operative on his conscience in early manhood, that he forbore to secure a high wrangler's ordinary share of Univer-sity preferment by formal, and what would have been, to him, insincere subscription.
In 1863 he wrote, "What is belief? A state of the mind. What is it often taken to be? An act of the mind. The imperative future tense -- I will believe thou shalt believe, &c. -- which has no existence except in the grammar-book, represents a futile attempt which people make upon themselves and upon others." This sentiment, expressed so forcibly in his later life, was the moving power which, when he was on the threshold of manhood, caused him to withdraw from the University in which he would, doubtless, have become a powerful leader of mathematical thought, had his religious feelings been less acute or his principles more elastic.
On coming to London, he entered at Lincoln's Inn, and would have been compelled to forsake mathematics for the study of the law, but that, in 1828, the University of London, now University College, was founded, and he was appointed to the mathematical chair. In May of the same year he became a Fellow of this Society, and in the following November gave his first introductory lecture at University College. In his own words, he then "began to teach himself to better purpose than he had been taught, as does every man who is not a fool, when he begins to teach others, let his former teachers have been what they may."
In 1837, ten years after his appointment at University College. he married Sophia Elizabeth, the daughter of Mr. William Frend, formerly a Fellow of Jesus College, Cambridge, author of several mathematical books, and Actuary of the Rock Life Assurance Office. The professional experiences of his father-in-law opened to De Morgan a fresh sphere of labour, in which he turned his mathematical acquirements to account in the service of many of the London Insurance Companies. In this new field of labour he might, doubtless, have made a much larger income than he could ever hope to derive from his professorship at University College, but he was devotedly attached to the principles of the new institution, and made it his first duty to advance its interests.
He was so punctual and so regular in the performance of his college duties that his passage to and from his classes served as a time-piece to observant students. Soon after eight o'clock every morning he might have been seen passing along the railed enclosure of University College, so absorbed in thought that his nearest friends might pass him without being recognised.
He remained a firm supporter of the institution and its principle of no religious tests till the year 1866, when the Council, in making an appointment to the chair of Logic and Mental Philosophy, refused, as the Professor believed, one of the candidates on account of his religious opinions. Professor De Morgan, acting under the conviction that the Institution to which he had devoted the best years of his life, was forsaking the leading principle on which it had been founded-a principle which from early manhood had influenced him, and was now dearer to him than ever felt it his duty to resign his professorship.
And thus, though deeply disappointed and grieved at the step he felt forced to take, Professor De Morgan, who had for nearly forty years been the chief honour and ornament of University College, left it, and, we are informed, never afterwards entered its gates.
To estimate the energy of the Professor, we must look at him not only as a teacher of mathematics, but as a mathematician, an actuary, a logician, an historian, a biographer, and a bibliophile.
First, then, as a teacher of mathematics; perhaps no man has been more successful in training distinguished mathematicians, amongst whom we may mention the names of Professor Clifton, Judge Hargreave, Mr. Routh, and Mr. Todhunter. Professor Sylvester also attended his lectures, though the relationship of professor and pupil did not in this case last very long. He had a method of interesting his hearers in the subjects on which he lectured, and of making them love mathematics for its own sake, to which few other men have ever attained. He devoted more time and labour to the logical processes by which the various rules are demonstrated than to the more technical parts of his subject, though of these too, in their proper place, Professor De Morgan was never unmindful, spending the greatest care on teaching the art of rapid and accurate computation.
His exposition of the elementary principles of the Differential Calculus, and of the logical processes of his Double Algebra, was most masterly and exhaustive, and was often enlivened by such humorous illustration that it never failed to impress itself upon the minds of his hearers. The subject matter of every lecture which he delivered was entered by him in a note-book, and was sent into the library of the college for the benefit of his pupils while writing out and expanding their own notes.
As a mathematician his work was so various that it would be difficult for any one man to review it; but we may allude, in passing, to his double algebra, which was certainly the forerunner of Quaternions, and contained the complete geometrical inter-pretation of the √-1. Sir William Rowan Hamilton, in the Preface to his Lectures on Quaternions, at p. 41, says: "But I wish to mention that, among the circumstances which assisted to prevent me from losing sight of the general subjects, and from wholly abandoning the attempt to turn to some useful account those early speculations of mine on triplets and on sets, was probably the publication of Prof. De Morgan's first paper on the Foundation of Algebra, of which he sent me a copy in 1841." And at p. 64 of the same Preface he says, in speaking of this theory of Sets of which he considered Quaternions (in their symbolical aspect) to be merely a particular case, "Before the publication of those sets, the closely connected conception of an 'algebra of the nth character' had occurred to Prof. De Morgan in 1844, avowedly as a suggestion from the Quaternions.' A great portion of his original investigations will be found in the form of communications to the Transactions of the Cambridge Philosophical Society."
As a writer of mathematical text-books he took the highest rank, his books being more suitable, however, for teachers than for pupils. They were characterised by extreme clearness, ex-haustiveness, and suggestiveness. Perhaps those best known are his Elements of Arithmetic, published 1830; his Elements of Algebra, published 1835; and his Differential and Integral Calculus, with Elementary Illustrations, which is a perfect mine of original thought, and in which some of the most important extensions which the subject has since received are distinctly foreshadowed. It was published by the Society for the Diffusion of Useful Knowledge.
His first mathematical text-book was a Translation of the Elements of Algebra by Bourdon, published when he was only twenty-two years of age. He wrote text-books upon trigonometry, double algebra, the theory of probabilities, connexion of number and magnitude, projection, and the use of the globes; besides which he edited more than one table of logarithms, and wrote prefaces and notes to the books of other mathematical authors. The list of his works and their various editions occu-pies nine pages of the British Museum Catalogue.
As an actuary he occupied the first place, though he was not directly associated with any particular office; but his opinion was sought for by professional actuaries on all sides, on the more difficult questions connected with the theory of probabilities, as applied to life-contingencies. In 1830 he wrote for the Cabinet Cyclopædia his "Essay on Probabilities," -- a book which still retains a high place among the literature of insurance offices.
As a logician he was well known, and his Formal Logic, together with the treatise of Dr. Boole, may be said to have created a new era in logical science. His controversy with Sir William Hamilton will long be remembered.
As an historian and biographer the English Encyclopædia says of him, that "he had a great affection for, and an extensive and minute erudition in, all kinds of literary history, biography, and antiquities." He was one of the most extensive contributors to the Penny Cyclopædia, many of the articles of scientific biography having been written by him, as well as most of the mathematical and astronomical articles. His contributions to the work are said to amount to one-sixth of the whole Cyclopædia. The lives of Newton and Halley, in Knight's British Worthies, were also from his pen. Besides these he published an index of the correspondence of the scientific men of the seventeenth century; and a book entitled General Information on Subjects of Chro-nology, Geography, Statistics, &c., References for the History of the Mathematical Sciences, 1842.
As a bibliophile, his Arithmetical Books from the Inven-tion of Printing to the present time, 1847, and his Budget of Paradoxes, will long remain celebrated. A reprint of the latter, greatly enlarged from manuscript notes left by the Professor, is now being taken through the press by his widow. He was the possessor of a very choice collection of mathematical works, which have, since his death, been purchased by Lord Overstone, and presented to the University of London, where they now form a De Morgan Library; most of the volumes contain bibliographical notes and sometimes quaint and humorous scraps from newspapers or other books pasted into their covers.
He was a true bibliophile, and revelled in all the mysteries of watermarks, title-pages, colophons, catchwords, and the like. He wrote in the preface-dedicatory of his list of arithmetical books, "The most worthless book of a bygone day, is a record worthy of preservation. Like a telescopic star, its obscurity may render it unavailable for most purposes; but it serves, in hands which know how to use it, to determine the places of more important bodies."
In addition to this, the Professor contributed largely to the Philosophical Magazine, the North British Review, the Athenaeum, the Companion to the Almanac, and Notes and Queries. The Athenæum says of him, that if all the articles which he contributed to literary and scientific journals were col-lected together, there would be found such a mass of literary achievement as seldom comes from the pen of a man whose sole business is to write for journals. He also compiled a Book of Almanacs, with an index of reference, by which the almanac may be found for every year up to A.D. 2000, with means of finding the day of the new moon from B.C. 2000 to A.D. 2000, published 1851.
The Professor also devoted much of his time to the business of this Society. For a period of more than thirty years he was officially connected with it, sometimes serving upon the Council, sometimes as Vice-President, and for many years as Secretary, in conjunction with Mr. Bishop and Admiral Manners, and dur-ing this period many of the volumes of the Monthly Notices were produced under his editorship.
He was the first President, and took great interest in the formation of the London Mathematical Society, of which his son, the late George Campbell De Morgan, was one of the first honorary secretaries. Soon after the untimely death of this son, who was a mathematician of considerable promise, he wrote to one of the early officers of the Mathematical Society, "My son's loss has thrown much grief over my house, but no gloom. He is spoken of as if he were removed to be followed in time, and to be kept in memory all the more, because he is no longer to remind us of himself by his direct presence. ... I make out distinctly, from written evidence among his papers, that you and he were the projectors of the Mathematical Society ... and I wish to have the evidence of this very distinctly preserved. There is quite enough in my hands to establish the fact, but I should be glad of every detail that you can remember."
A very inadequate notion of Professor De Morgan will be formed by those who look only at his works. From them, indeed, it will be seen that he was a reader who relished every kind of intellectual food, and a thinker whose subtlety was only surpassed by his originality. They abound also with proof that he overflowed with humour; but his familiar associates alone can render justice to the versatility of his powers and the sweet-ness of his disposition.
Knowing many subjects thoroughly, there was scarcely one about which he did not know much. He passed, for diversion's sake, from one arduous study to another, but though he found a pastime in intellectual efforts that would exhaust ordinary students, he did not disdain literature that pedants are apt to contemn as frivolous. He was an habitual and eager reader of novels, especially humorous novels, but there were times when, in the absence of a good novel, he could enjoy a bad one. The paradoxers, whom he infuriated by his banter, were strangely at fault when they accused him of malignity. He was the kindliest, as well as the most learned, of men -- benignant to every one who approached him, never forgetting the claims which weakness has on strength. Soon after the death of his son the Professor was attacked with a disease of the kidneys, which during more than two years of distressing illness reduced him to a shadow of his former self; and on Saturday, the 18th of March, 1871, at one o'clock in the afternoon, his spirit was released from the body, which had long been only a burden to it.
Augustus De Morgan's obituary appeared in Monthly Notices of the Royal Astronomical Society 32:4 (1872), 112-118.