Correspondence with Dr. S.G. Howe.--Bearing of the War on the
Position of the Negro Race.--Affection for Harvard College.
--Interest in her General Progress.--Correspondence with Emerson
concerning Harvard.--Glacial Phenomena in Maine.

CHAPTER 21.

1865-1868: AGE 58-61.

Letter to his Mother announcing Journey to Brazil.--Sketch of
Journey.--Kindness of the Emperor.--Liberality of the Brazilian
Government.--Correspondence with Charles Sumner.--Letter to his
Mother at Close of Brazil Journey.--Letter from Martius concerning
Journey in Brazil.--Return to Cambridge.--Lectures in Boston and
New York.--Summer at Nahant.--Letter to Professor Peirce on the
Survey of Boston Harbor.--Death of his Mother.--Illness.
--Correspondence with Oswald Heer.--Summer Journey in the West.
--Cornell University.--Letter from Longfellow.

CHAPTER 22.

1868-1871: AGE 61-64.

New Subscription to Museum.--Additional Buildings.--Arrangement of
New Collections.--Dredging Expedition on Board the Bibb.--Address
at the Humboldt Centennial.--Attack on the Brain.--Suspension of
Work.--Working Force at the Museum.--New Accessions.--Letter from
Professor Sedgwick.--Letter from Professor Deshayes.--Restored
Health.--Hassler Voyage proposed.--Acceptance.--Scientific