566 



SCIENCE. 



[Vol. I., No. 20. 



tent tentative in tlieir nature, have furnished 

 results of great interest and vaUie to the navi- 

 gator, have stimulated later researches, and 

 have led to the adoption of a definite plan, 

 according to which have been made the obser- 

 vations for depth and temperature in the waters 

 of the Gulf of Mexico, the Caribbean Sea, and 

 in those off the Atlantic coast of the United 

 States. 



At as early a date as practicable after the 

 close of the civil war, a systematic investigation 

 was begun by deep-sea sounding and dredging, 

 combined with observations of surface, serial, 

 and bottom temperatures, and of currents, in 

 the Gulf Stream and in the Gulf of Mexico. 



In a communication made to the National 

 academy of sciences in 1880 by J. E. Hil- 

 gard, M.N.A.S. {Amer. journ. sc, April, 

 1881), upon a model of the Gulf of Mexico, a 

 condensed statement is given of the results of 

 the exploration of the basin of this great in- 

 land sea, as derived from the work organized 

 bj' Benjamin Peirce and Carlile P. Patterson, 

 superintendents of the U. S. coast-survey. 

 This exploration was begun by Assistants 

 L. F. Pourtalfes and Henry Mitchell, U. S. 

 coast-survey, with the aid of Master R. Piatt, 

 U.S.N., in 1868, and continued bj^ Comman- 

 ders J. A. Howell and C. D. Sigsbee, 

 U.S.N. , in 1872-74 and 1875-78, in the coast- 

 survey steamer Blake. With the improved 

 methods of sounding, and the mechanical 

 appliances perfected hy Commander Sigsbee, 

 the work in the Gulf of Mexico was brought 

 to a successful conclusion, and under Com- 

 mander J. R. Bartlett, U.S.N. , it was ex- 

 tended to the Caribbean Sea. 



Sketch no. 21, Coast and geodetic survej' 

 report for 1879, shows the soundings in these 

 waters and their approaches, in depths ranging 

 from 100 to upwards of 3,400 fathoms. 



Similar investigations have since been pros- 

 ecuted bj- Commanders Bartlett and Brownson, 

 U.S.N., underthe direction of Superintendents 

 Patterson and Hilgard of the coast-survej', in 

 the western part of the North Atlantic, — that 

 great embayment, which, limited by New- 

 foundland on the north, and by the Windward 

 Islands on the south, might be not inaptlj' 

 named the Gulf of North America. 



The depths and temperatures obtained by 

 these officers, npon lines run normal to the 

 coast across the course of the Gulf Stream, 

 and upon other lines connecting with those run 

 b}- II. M. S. Challenger in 1873, are shown 

 upon the accompanying chart. A reference 

 to it will make apparent the part taken by the 

 coast-survey in developing the configuration 



of the ocean-bed between the Bermudas and 

 the West India Islands, and northward to the 

 banks of Newfoundland, and in defining the 

 limits of the continental plateau, which, ex- 

 tending from the coast to the 100-fathom line, 

 may be described as the western rim of this 

 great basin of the North Atlantic. 



It was from these explorations that data 

 were derived for the construction at the coast- 

 survey office of the relief model of the- western 

 part of the North Atlantic, now on exhibition 

 at the London international exposition of fish 

 and fisheries. 



Some interesting details of his work have 

 been communicated by Commander Bartlett, 

 who, during the summer of 1880, was engaged 

 in dredging and sounding off' the coast in the 

 vicinitj^ of Charleston, S.C. The first line 

 run revealed the remarkable character of the 

 bottom. 



The first sounding and haul was made in 

 142 fathoms, south-east of Cape Romain. 

 After this, in steaming to the eastward, taking 

 frequent casts to find the depth at which it 

 was desired to dredge, to their astonishment 

 the water did not deepen as thej^ expected, 

 and they had crossed the supposed axis of 

 the Gulf Stream before getting 300 fathoms at 

 anj^ sounding. Commander Bartlett, in his 

 report, says, "The bottom was hard coral 

 rock, but the sounding-rod always brought up 

 small fragments of coral. We found but very 

 few traces of animal life qn this bottom, but 

 made good hauls on its edge. For fifteen 

 miles or more from the 100-fathom line we 

 found a very strong current setting to the 

 south-west. When the trawl was down, we 

 tailed in that direction, and dragged at the 

 rate of 2 knots without steam. When in 

 the Gulf Stream, we found the current to the 

 northward and eastward 2.6 knots per hour. 

 The water deepened east of the axis to 382 

 fathoms, but shoaled again to 337 fathoms." 



The lines run during this and the following 

 season showed the same unmistakable plateau 

 extending from Cape Ilatteras to the Bahama 

 Banks, the depths increasing but slowly until 

 about 500 fathoms, after which they increased 

 rapidl}^ to the great Atlantic basin, at a depth 

 of between 2,000 and 3,000 fathoms. 



Commander Bartlett says in his report of 

 the second season, after completing this work, 

 "The eighteen lines of soundings run normal 

 to the coast from Jupiter Inlet, Fla., to Curri- 

 tuck, N.C., by the steamer Blake; and the 

 observations taken by the hydrographic partj' 

 under my command gave very interesting data 

 in regard to the phj-sical features of the bottom 



