_April 4th._—It has occurred to Mr. Agassiz, as a means of preparing the young men who accompany him for the work before them, to give a course of lectures on ship-board. Some preparation of the kind is the more necessary, since much of the work must be done independently of him, as it will be impossible for so large a party to travel together; and the instructions needed will be more easily given in a daily lecture to all, than in separate conversations with each one singly. The idea finds general favor. The large saloon makes an excellent lecture-room; a couple of leaves from the dining-table with a black oil-cloth stretched across them serve as a blackboard. The audience consists, not only of our own company, but includes the few ladies who are on board, Mr. Bradbury, the captain of our steamer, Bishop Potter, some of the ship’s officers, and a few additional passengers, all of whom seem to think the lecture a pleasant break in the monotony of a sea voyage. To-day the subject was naturally suggested by the seaweeds of the Gulf Stream, so recently caught and so crowded with life,—“A lecture on the Gulf Stream in the Gulf Stream,” as one of the listeners suggests. It was opened, however, by a few words on the exceptional character of the position of this scientific commission on board the Colorado. “Fifty years ago, when naturalists carried their investigations to distant lands, either government was obliged to provide an expensive outfit for them, or, if they had no such patronage, scanty opportunities grudgingly given might be granted them on ordinary conveyances. Even if such accommodation were allowed them, their presence was looked upon as a nuisance: no general interest was felt in their objects; it was much if they were permitted, on board some vessel, to have their bucket of specimens in a corner, which any sailor might kick over, unreproved, if it chanced to stand in his way. This ship, and the spirit prevailing in her command, opens to me a vista such as I never dreamed of till I stood upon her deck. Here, in place of the meagre chances I remember in old times, the facilities could hardly be greater if the ship had been built as a scientific laboratory. If any such occasion has ever been known before, if any naturalist has ever been treated with such consideration, and found such intelligent appreciation of his highest aims, on board a merchant-ship fitted up for purposes of trade, I am not aware of it. I hope the first trip of the Colorado will be remembered in the annals of science. I, at least, shall know whom to thank for an opportunity so unique. This voyage, and the circumstances connected with it, are, to me, the signs of a good time coming; when men of different interests will help each other; when naturalists will be more liberal and sailors more cultivated, and natural science and navigation will work hand in hand. And now for my lecture,—my first lecture on ship-board.”