Mrs. Somerville’s other works, written after _The Mechanism of the Heavens_, were _The Connection of the Physical Sciences_, _Physical Geography_, and _Molecular and Microscopic Science_. The last book was commenced after she had completed her eightieth year. Her mental powers remained unimpaired to a remarkably late period, and she also had extraordinary physical vigour to the end of her life. She affords a striking instance of the fallacy of supposing that intellectual labour undermines the physical strength of women. Her last occupations, continued till the actual day of her death, were the revision and completion of a treatise on _The Theory of Differences_, and the study of a book on _Quaternions_. Her only physical infirmity in extreme old age was deafness. She was able to go out and enjoy life up to the time of her death, which took place in 1872, at the great age of ninety-two years. She was a woman of deep and strong religious feeling. Her beautiful character shines through every word and action of her life. Her deep humility was very striking, as was also her tenderness for, and her sympathy with, the sufferings of all who were wretched and oppressed. One of the last entries in her journal refers again to her love of animals, and she says, “Among the numerous plans for the education of the young, let us hope that mercy may be taught as a part of religion.” The reflections in these last pages of her diary give such a lovely picture of serene, noble, and dignified old age that they may well be quoted here. They show the warm heart of the generous woman, as well as the trained intellect of a reverent student of the laws of nature. “Though far advanced in years, I take as lively an interest as ever in passing events. I regret that I shall not live to know the result of the expedition to determine the currents of the ocean, the distance of the earth from the sun determined by the transits of Venus, and the source of the most renowned of rivers, the discovery of which will immortalise the name of Dr. Livingstone. But I regret most of all that I shall not see the suppression of the most atrocious system of slavery that ever disgraced humanity—that made known to the world by Dr. Livingstone and by Mr. Stanley, and which Sir Bartle Frere has gone to suppress, by order of the British Government.” A later entry still, and the last, gives another view of her happy, faithful spirit. The Admiral’s daughter speaks in it: “The Blue Peter has been long flying at my foremast, and now that I am in my ninety-second year I must soon expect the signal for sailing. It is a solemn voyage, but it does not disturb my tranquillity. Deeply sensible of my utter unworthiness, and profoundly grateful for the innumerable blessings I have received, I trust in the infinite mercy of my Almighty Creator.” She then expresses her gratitude for the loving care of her daughters, and her journal concludes with the words, “I am