I enclose you a copy of my paper on Earthquakes.—² I have grown older, since I wrote it, & therefore, I hope, a little wiser, & as a consequence set less value on theoretical reasoning in geology—but I even yet think there is some weight in the argument, respecting the necessary slow elevation of mountain chains, which have protuberant axes of Plutonic rock.— Should you read my paper, & have at any future time, (although I well know how much your time must be occupied) leisure to tell me what you think of it, I should feel very great interest in hearing from you—

Believe me my dear Sir | Your’s most truly | Chas. Darwin