SPECIFIC GRAVITIES. 27 



Mr. F. M. Chamberlain made two daily observations of the density of 

 the water, and found the same discrepancies between our observations and 

 those of 1891, and those given by the " Challenger " and in the Atlas of 

 the Pacific Ocean published by the German Naval Observatory. Whenever 

 we took a serial temperature, he also determined the density at 800 fathoms. 



The observations made in 1891 were not sufficiently numerous to enable 

 me to draw the curves of densities in the Panamic district and connect them 

 with the observations taken during the present cruise. They varied so 

 rapidly from station to station as to indicate great difference in densities in 

 belts of water separating adjoining stations. This rendered it impracticable 

 to sketch out a chart of the densities of the Panamic region from the con- 

 fused data available. 



From the effect of the prevailing southeasterly trades and the northerly 

 set of the Humboldt current off the South American continent the lines of 

 equal gravity are frequently separated by narrow belts of different gravities. 

 This is well shown on PI. 3'', in the area between the curves of 1.0250 and 

 of 1.0255 off the coast of Peru, as far north as Aguja Point and half-way 

 from Callao to Easter Island. 



This confusion becomes still greater in the Panamic district north of the 

 equator and to the east of the line run by the "Albatross" from Mariato 

 Point to the Galapagos. The densities increase in a southwesterly direction 

 from Acapulco, from 1.0240 to 1.0245, 1.0250, 1.0255, and 1.02G0. These 

 lines are about 600 miles apart, and all trend in a southeasterly direction. 

 The area of greatest specific gravity is enclosed by the 1.0200 line which runs 

 from a point north of the Marquesas to about 300 miles northeast of Easter 

 Island, where the line forms a loop and runs towards Manga Reva about 

 half-way between Easter Island and the equator. The 1.0255 line coming 

 from Moser Basin runs east and then, forming a sharp elbow, south, about 

 parallel with the South American coast line. The 1.0250 curve runs in a 

 general way about parallel with the 1.0255 and 1.0260 curves and makes 

 a sharp angle off Aguja Point and runs soutli in loops about parallel to the 

 coast off Callao. Towards Acapulco only parts of the 1.0240 and 1.0245 

 curves are indicated parallel to the 1.0250 line. On the line from the 

 Galapagos to Acapulco an area of greater density is indicated, with a 

 specific gravity of 1.0256. This area crosses the belt of hot water with 

 a temperature of 78" to 80" lying to the west of Cocos Island and extending 

 westward to the Moser Basin. 



