“ De Morgan’s mathematical writings contributed powerfully towards the progress of the science. His memoirs on the “Foundation of Algebra,” in the 7th and 8th volumes of the Cambridge Philosophical Transactions, contain some of the most important contributions which have been made to the philosophy of mathematical method; and Sir W. Rowan Hamilton, in the preface to his Lectures on Quaternions, refers more than once to those papers as having led and encouraged him in the working out of the new system of quaternions. ”

“ These papers taken together constitute a great treatise on logic, in which he substituted improved systems of notation, and developed a new logic of relations, and a new onymatic system of logical expression. In 1860 De Morgan endeavoured to render their contents better known by publishing a Syllabus of a Proposed System of Logic, from which may be obtained a good idea of his symbolic system, but the more readable and interesting discussions contained in the memoirs are of necessity omitted. The article “Logic” in the English Cyclopaedia (1860) completes the list of his logical publications. ”

“ This latter work consists of articles most of which were originally published in the Athenaeum, describing the various attempts which have been made to invent a perpetual motion, to square the circle, or to trisect the angle; but De Morgan took the opportunity to include many curious bits gathered from his extensive reading, so that the Budget, as reprinted by his widow (1872) , with much additional matter prepared by himself, forms a remarkable collection of scientific ana. De Morgan’s correspondence with contemporary scientific men was very extensive and full of interest. ”

“ But later in life he became even better known to the literary world by his novels, Joseph Vance (1906) , Alice for Short (1907) , Somehow Good (1908) and It Never Can Happen Again (1909) , in which the influence of Dickens and of his own earlier family life were conspicuous. ”

“ He also wrote biographies of Sir Isaac Newton and Edmund Halley for Knight’s British Worthies, various notices of scientific men for the Gallery of Portraits, and for the uncompleted Biographical Dictionary of the Useful Knowledge Society, and at least seven articles in Smith’s Dictionary of Greek and Roman Biography. Some of De Morgan’s most interesting and useful minor writings are to be found in the Companions to the British Almanack, to which he contributed without fail one article each year from 1831 up to 1857 inclusive. ”