to popularise many of the sciences, particularly physiology. His last years were devoted to philosophical questions, and his "Problems of Life and Mind" were published in fragments, the concluding volume, under George Eliot's editorship, after his death. The earliest writer of the era to popularise science was =Sir David Brewster (1781-1868)=, an eminent physicist, in whose _Edinburgh Cyclopædia_ Carlyle commenced his literary career. His "Life of Newton," "Martyrs of Science," and "More Worlds than One" are still widely read. =Michael Faraday (1791-1867)=, another famous physicist, is still better remembered by our own generation, principally for his popular lectures at the Royal Institution, where he was superintendent of the laboratory for forty-eight years. He was a blacksmith's son, and was originally apprenticed to a bookbinder. After his discovery of magneto-electricity, he had, he told Tyndall, a hard struggle to decide whether he should make wealth or science the pursuit of his life. Tyndall calculates that Faraday could easily have realised £150,000; but he declared for science and died a poor man. =John Tyndall (1820-1893)=, who once said that it was his great ambition to play the part of Schiller to this Goethe, succeeded Faraday at the Royal Institution, and wrote about him eloquently in his "Faraday as a Discoverer." Tyndall was born at Leighlin Bridge, Carlow, Ireland, in 1820. His father was a member of the Irish constabulary. His services to many branches of science were great; but he concerns us here not so much by his treatises on electricity, sound, light, and heat, or by his discoveries in diamagnetism, as by his "Lectures on Science for Unscientific People," which, Huxley said, was the most scientific book he had ever read, and which has yet the transcendent merit of giving enjoyment as well as instruction, even to the readers of three-volume novels. In 1856 Tyndall made a journey to Switzerland, in company with Professor Huxley, and the friends afterwards wrote a treatise "On the Structure and Motion of Glaciers." Geological treatises may be said to have given the fullest play to the literary side of science. The work of Robert Bentley and Sir Joseph Hooker in botany, of Michael Foster, St George Mivart, and Francis Maitland Balfour in biology, is, it may be, equal or superior to that of the bulk of the writers whose achievements we have chronicled; but it is not a part of literature. Burdon Sanderson, Balfour Stewart, and a host of other men, have done incalculable service in the Victorian era--service, it is to be feared, which scarcely obtains as generous recognition as the cheap generalisations of smaller men; but scientific text-books, however important, are scarcely within the scope of these chapters. Geology, on the other hand, is, as it were, a conglomerate of the sciences, and lends itself readily to the most eloquent literary expression. Few writers have been more widely read than =Hugh Miller (1802-1856)=, a