Page:Popular Science Monthly Volume 77.djvu/438

432 Havana, Cuba, in December, 1877, and remained on board until April, 1878, exploring the Gulf of Mexico, and adjacent regions. Admiral, then Lieutenant Commander C. D. Sigsbee, U.S.N., was in command, and his ingenious inventions of sounding apparatus, trawls, etc., enabled the expedition to accomplish unprecedented results.

The second cruise of the Blake started from Washington on November 27, 1878, with Captain J. R. Bartlett, U.S.N., in command, and throughout the winter of 1878-79 they cruised among the Windward Isles of the West Indies and over the Caribbean Sea, visiting Havana, Jamaica, Hayti, Porto Rico, St. Thomas, Santa Cruz, Montserrat, St. Kitts, Guadeloupe, Dominica, Martinique, St. Lucia, St. Vincent, Granadines, Grenada and Barbados, and gathering an immense collection of animals from the depths of the ocean.

The third and last cruise of the Blake was for the purpose of sounding the depths of the Gulf Stream. They started from Newport in June and cruised until August, 1880, running seven lines of soundings off the coast between Charleston and George's Bank, which led to the discovery that a plateau covered by water not more than 600 fathoms deep extends from the Bahamas northward to Cape Hatteras, forming a vast triangular area of shallow water, the outer edge of which is from 300 to 350 miles out in the ocean from the coast of the Southern Atlantic States. The Gulf Stream flows across this area on its course between the Straits of Bernini to Cape Hatteras, and the outer edge of this shallow bank is » here the North American continent rises abruptly from the depths of the flat floor of the ocean. The name "Blake Plateau" was most appropriately given by Alexander Agassiz to this extensive area of shallow water.

During her three cruises the Blake made 355 soundings, deep-sea temperature observations, and trawl hauls yielding a phenomenally rich harvest of new and interesting marine animals. Among other things, the second cruise led to the discovery of a vast submarine valley, the "Bartlett Deep," extending for nearly 700 miles along the southern coast of Cuba toward Honduras. Twenty miles south of Grand Cayman this great depression is 3,400 fathoms deep, so that the summits of the mountains of Cuba only 50 miles away are 28,000 feet above its somber trough.

This experience upon the Blake was the most momentous event in Alexander Agassiz's scientific life, for it gave him a taste for marine exploration which was to dominate his future career. Without this he might have continued to be an embryologist and systematic zoologist, but he was destined to more conspicuous achievements as an explorer. Its effect upon the history of the Museum at Cambridge was also profound, for the output of museum publications had been so slow that at the end of 1877 only three volumes of the "Bulletins" and five