FIRST SUNDAY AT SEA.—GULF STREAM.—GULF-WEED.—LECTURES PROPOSED.—FIRST LECTURE: “ON THE GULF STREAM IN THE GULF STREAM.”—AQUARIUM ESTABLISHED ON BOARD.—SECOND LECTURE.—ROUGH SEA.—PECULIAR TINT OF WATER.—THIRD LECTURE: LAYING OUT WORK OF EXPEDITION IN BRAZIL; DISTRIBUTION OF FISHES IN BRAZILIAN RIVERS; ITS BEARING ON ORIGIN OF SPECIES; COLLECTING OF EGGS.—TROPICAL SUNSET.—FOURTH LECTURE: PLAN OF GEOLOGICAL INVESTIGATIONS WITH SPECIAL REFERENCE TO GLACIAL PHENOMENA IN SOUTH AMERICA.—FLYING-FISH.—FIFTH LECTURE: GLACIAL PHENOMENA, CONTINUED.—SECOND SUNDAY AT SEA.—ROUGH WATER.—SIXTH LECTURE: EMBRYOLOGICAL INVESTIGATIONS AS A GUIDE TO SOUND CLASSIFICATION.—SEVENTH LECTURE.—MOONLIGHT NIGHTS.—TRADE-WINDS.—EIGHTH LECTURE: IMPORTANCE OF PRECISION IN LOCALIZING SPECIMENS.—SOUTHERN CROSS.—NINTH LECTURE: FRESH-WATER FISHES OF BRAZIL.—EASTER SUNDAY.—FIRST SIGHT OF SOUTH AMERICAN SHORE.—OLINDA.—PERNAMBUCO.—CATAMARANS.—TENTH LECTURE: METHODS OF COLLECTING.—ELEVENTH LECTURE: CLASSIFICATION OF FISHES, AS ILLUSTRATED BY EMBRYOLOGY.—PREPARATIONS FOR ARRIVAL.—TWELFTH LECTURE: PRACTICAL LESSON IN EMBRYOLOGY—CLOSING LECTURE: TRANSMUTATION THEORY; INTELLECTUAL AND POLITICAL INDEPENDENCE.—RESOLUTIONS AND SPEECHES.—SINGULAR RED PATCHES ON THE SURFACE OF THE SEA. _April 2d, 1865._—Our first Sunday at sea. The weather is delicious, the ship as steady as anything on the water can be, and even the most forlorn of our party have little excuse for sea-sickness. We have had service from Bishop Potter this morning, and since then we have been on deck reading, walking, watching a singular cloud, which the captain says is a cloud of smoke, in the direction of Petersburg. We think it may be the smoke of a great decisive engagement going on while we sail peacefully along. What it means, or how the battle ends, if battle it be, we shall not know for two months perhaps.[2] Mr. Agassiz is busy to-day in taking notes, at regular intervals, of the temperature of the water, as we approach the Gulf Stream. To-night we cut it at right angles, and he will remain on deck to continue his observations.