90 



SCIENCE. 



[Vol. V., No. 104. 



temperature of 39 J°. This established the 

 continuity of the rim, and consequently the 

 truth of the deduction made from the exami- 

 nation of the temperatures of the waters of the 

 Gulf of Mexico. 



That part of the Caribbean Sea west of the 

 Island of Jamaica, and the Pedro and Rosalind 

 banks, were thoroughly sounded in the winter 

 of 1880-81 ; and the Cayman Islands and the 

 Misteriosa Bank were found to be part of a sub- 

 marine extension of the range running along 

 the south-east side of Cuba. 



Immediately south of these partially sub- 

 merged peaks was an immense deep valley, 

 extending from between Cuba and Jamaica as 



"Depth Temperatures Depth 



Sirriiiee 80° Surface 



DIAGRAM OF 1UDGE CONNECTING CUBA WITH HAYTI. 



far as the Gulf of Honduras. This valley is 

 narrow at its eastern end, but widens between 

 the western end of Jamaica and Cape Cruz, 

 where the soundings were 3,000 fathoms within 

 tifteen miles of Cuba, and '2,800 fathoms within 

 twenty-five miles of Jamaica. This valley is 

 700 miles long, with an average breadth of 80 

 miles. The greatest depth was 3,428 fathoms, 

 just south of the Island of Grand Cayman. 

 Between Misteriosa Bank and Chinchorro 

 Bank, the soundings were regular at 2,500 

 fathoms. North of Misteriosa and Grand 

 Cayman, to the Isle of Pines and Cape San 

 Antonio, the soundings were generally 2,500 

 fathoms. So much for the western Carib- 

 bean. 



The lines of deep-sea soundings taken by 

 Lieut. -Commander Tanner in the Albatross last 

 winter, were first from the east end of Puerto 



Rico to Bird Island, thence nearly south to Trin- 

 idad, and then north-west towards the Mona 

 Passage. These lines, in connection with that 

 which I ran with the Blake from the island of 

 Dominica to Bird Island, and back to Monser- 

 rat, clearly developed a submarine elevation 

 reaching north and south nearl} T parallel to the 

 main chain of islands from Granada to St. 

 Christopher ; the depth on this ridge being 

 considerably less than 1,000 fathoms, with 

 1,500 and 2,000 fathoms on each side. 



From the Mona Passage a line was run to 

 Los Roques, thence to the mainland, and then 

 to Curacoa. The soundings south of this 

 chain of islands gave a greatest depth of 1,030 

 fathoms. A line was run from Curacoa to 

 Beata Island, at the extreme south point of 

 Santo Domingo. A line was also run from 

 Morant Cays, off the east end of Jamaica, to 

 the mouth of the Magdalena River, and then 

 across the Rosalind Banks. 



These several lines show an immense basin 

 of nearly the same depth, extending from Santo 

 Domingo and Puerto Rico to the shores of 

 the Spanish Main, and over an area of more 

 than 200,000 square miles, without any appar- 

 ent inequality of surface. A line drawn from 

 the west end of Santo Domingo to Cartagena 

 shows a depth of 2,200 fathoms. The floor 

 of the basin then rises gradually to the banks 

 connecting the island of Jamaica with the 

 Mosquito Bank. 



The basin is a few hundred fathoms deeper 

 in its eastern part, but rises abruptly to the 

 submarine elevation previously mentioned. A 

 very remarkable depression will be observed in 

 the Atlantic, north of Puerto Rico. Lieut. - 

 Commander Brownson here obtained a depth 

 of 4,561 fathoms. Additional soundings will 

 be taken, when a vessel is available, for more 

 details over the ridge of which Bird Island 

 forms a part ; but the general basin is prob- 

 ably correctly portrayed. 



The soundings connecting the islands and 

 various banks, and to determine the depths 

 of the western Caribbean, have alread3 T been 

 made in detail. This work, so eminently with- 

 in the province of the nav} T , and performed 

 with so much success by naval officers, should 

 be continued, and I hope to obtain man}' new 

 soundings this summer. 



The model also shows the elevations of adja- 

 cent shores and islands. The horizontal scale 

 is 33 miles to the inch ; vertical, 6,000 feet or 

 1,000 fathoms to the inch. The latter, though 

 so much distorted, was necessary to give the 

 smaller elevations and depressions. 



Even with this scale, the highest mountain 



