April 25. — I returned to Boston to attend the third annual meeting of the Association of American Geologists, who had held their previous meetings of 1840 and 1841 at Philadelphia. On the present occasion Dr. Morton took the chair, and in the course of the week papers were read and freely discussed on a variety of scientific questions by many of the leading American geologists, some of whom had come from distant parts of the Union. The patronage afforded by the state surveys has created a numerous class both of practised observers and able writers. Among those engaged in these government undertakings, who took part in these proceedings, I may mention Professor Hitchcock, of Massachusetts, Professor W.B.Rogers, of Virginia, Professor H. D. Rogers, of Pennsylvania, Mr. Vanuxem, Dr. Emmons, Mr. Hall, and Dr. Beck — all engaged on the survey of New York; Dr. Jackson, who has surveyed Rhode Island, New Hampshire, and Maine; and Dr. Locke, of Ohio. There were also present Professor Silliman and his son, Messrs. Nicollet, Redfield, Gould, Bailey, Dana, Couthouy, Haldeman, Hubbard, J. L. Hayes, and others, all known as authors or contributors to scientific publications The structure of the Alleghany Hills, and of the coal-fields of America, the origin of coral reefs, the glacial theory, the effects of icebergs, the nature of the foot-marks in the red sandstone of Connecticut valley, and other subjects, were debated upon during the week, in an animated but most amicable style.