HYDROGRAPHY. 315 



Mexico, from Acapulco to the Tartar Shoal, where the mail- 

 steamer City of San Francisco was lost, and west of Aca- 

 pulco as far as Mangrove Bluff, besides making plans of Aca- 

 pulco and Sihuantenejo harbors and the anchorages of Te- 

 quepa and Petatlan. These charts are now being prepared 

 for publication. Commander Philip has also made a series 

 of valuable deep-sea soundings off and on shore between San 

 Diego and Cape San Lucas, and is now engaged in continu- 

 ing the survey of the Pacific coast from Cape Corrientes to 

 the Gulf of Fonseca. 



Commander Selfridge, U.S.N., in the U.S.S. Enterprise, has 

 made a most valuable track-survey of the Amazon River, 

 from Para to the mouth of the Madeira, and of the latter 

 river as far as the rapids of San Antonio, a distance of 1300 

 miles. The charts of this survey are being rapidly prepared 

 for publication; the sheets of the Amazon on a scale of half 

 an inch to the mile, and those of the Madeira River on a scale 

 of one inch to the mile. At fifty-five stations, separated by 

 only short distances, careful astronomical and hypsometricai 

 observations were made. The general conclusions derived 

 are, that no serious obstacles to navigation need be appre- 

 hended at any season below the rapids of San Antonio, a 

 depth of ten fathoms for the Amazon, and of three to four 

 fathoms for the Madeira, being the minimum. 



A railway now being constructed round the rapids (which 

 are nearly two hundred miles in extent) to the mouth of the 

 Mamore River will enable merchandise and passengers to 

 reach Bolivia without difficulty, and will doubtless very ma- 

 terially stimulate commerce with this hitherto almost inac- 

 cessible region. 



Lieut.-Commander Gorrino-e, U.S.N., has been eno-a^ed in 

 the U.S.S. Gettysburg in collecting information for compiling 

 sailing directions for the shores of the Mediterranean. 



The officers of the U.S.S. Guard have continued the work 

 undertaken by the United States Hydrographic Office, of de- 

 termining secondary meridians of longitude by means of sub- 

 marine telegraph cables, having measured from the Royal 

 Observatory at Lisbon, by way of Madeira, Cape de Verde 

 islands, Pernambuco, Rio de Janeiro, and Monte Video, to 

 Buenos Ayres, connecting with the chain of longitudes meas- 

 ured by Dr. B. A. Gould, from the National Observatory at 



