Lyell’s long-expected book on the “Principles of Geology” was published in 1830, and it made a very considerable sensation, and was warmly combated and abused. Now it is admitted as the most conclusive and useful of introductory books, fit for a youth, and eminently good in its tone. Then the man, ever on the move, left for the Pyrenees, and studied the formations there, and especially devoted himself to the explanation of ripple-marks in the hundreds of feet of rock, and noticed the effects of water-borne and air-carried sand in accumulating flats of ripples one over the other. In 1831 Lyell accepted the position of Professor of Geology in King’s College, London, and he gave courses of lectures there in 1832 and 1833; and he became engaged to Mary, the eldest daughter of Mr. Leonard Horner, a geologist of considerable reputation, and a thoroughly liberal-minded man. Mr. Horner was a great friend of Lyell’s before the engagement, and was a most painstaking man and a great manager at the Geological Society. Lyell’s letters to Miss Horner are most interesting, and show how admirable a woman she was and how she stimulated him to follow out his great destiny. His work on the “Principles” became a great pecuniary success, and he laboured hard at King’s College, and was much annoyed at the decision of the council at the College, not to allow women to attend his lectures, which were a great success. Married, Lyell started for Germany, the Rhine, and Switzerland. Coming home to London, he set to work at his lectures at the Royal Institution, where ladies were admitted, and at King’s College, where they were not. He had two hundred and fifty people to hear his introductory lecture at King’s College, and it dwindled down to fifteen in a few days, not from any want of care or excellence in Lyell, who was ever bitter against the establishment for their refusal to advance female education. He retired from the professorship as soon as he found that it interfered with his researches, and never again took any part in academical teaching. The trouble he took about his lectures was great, and he went to great expense in having diagrams well drawn. His retirement was a great loss to the College, which now admits ladies to certain lectures. In 1834, Lyell travelled in Sweden and examined into the rise of the land in Scandinavia, and whilst enjoying his hard geological work—for he was well received by everybody, and taken to see everything—his letters show how he missed his gentle and sympathizing wife. On his return home Lyell received one of the Royal Society medals for his work on the “Principles of Geology,” and in 1838 became President of the Geological Society. About this time his attention was strongly drawn to the relative numbers of living species found in the strata which had been formed during the last geological or tertiary age. In working at Sicily he had found that in the latest beds in which the shells were