HISTORICAL SKETCH OF DEEP-SEA WORK. 49 
successors, Professor Benjamin Peirce, Carlile P. Patterson, and 
Julius E. Hilgard, into the most important hydrographic coast 
exploration yet undertaken by any government. With a wise 
liberality, secondary hydrographie scientific problems, mainly of 
interest to the biologist and geologist, have been connected with 
the work of the United States Coast Survey, while sections 
were earried on aeross the Gulf Stream under the direction of 
Lieutenant Craven in 1855, and subsequently. under that of 
Lieutenants Maffitt, Murray, Sands, Bache, Davis, and others. 
In 1850 the extended biological survey of the Florida reefs by 
Professor L. Agassiz was undertaken at the request of the U. S. 
Coast Survey. The beginning of a more systematic deep-sea 
exploration was made by Pourtalés and Mitchell, assistants of 
the U. S. Coast Survey, in 1867. During the explorations 
of Pourtalés of that year, and of 1868 in the “Corwin” and 
* Bibb," dredging operations were carried on between Florida 
and Cuba, and a depth of 850 fathoms was reached. The 
collections were most interesting, and the first publications 
of the results of the corals and echinoderms by L. F. Pour- 
talés and A. Agassiz showed as clearly as possible the antique 
character of the fauna then discovered, and the relationship 
which it indicated to the cretaceous period, rather than to the 
animals living upon the adjoining shores. An immense number 
of new types were also discovered, and it became very plain that 
the fauna living on the bottom along the course of the Gulf 
Stream was one of the most interesting known to science. 
The character of the bottom samples also first showed to 
Agassiz that the deposits going on at the bottom of the ocean, 
at great depths, were very different from the shore deposits 
which as a general rule characterize all geological formations ; * 
and that the modern chalk was not very different probably from 
the old chalk of the cretaceous period. The expedition of the 
United States Coast Survey steamer “ Hassler,” Commander 
Johnson (1871), which sailed with Professor L. Agassiz from 
Boston to San Francisco, did not fulfil the expectations of its 
projectors. 
! Among the earlier publications re- France et des Mers principales du Globe. 
lating to the nature of the off-shore bot- Paris, 1871. 
tom, see Delesse, Lithologie des Mers de : 
