cxx GENERAL SUMMARY OF SCIENTIFIC AND 



HYDROGRAPHY. 



By Lieutenant-Commander F. M, GREEN, U. S. N. 



The most strongly marked feature of hydrograpliic work for the 

 past year is the careful exploration of the depth and temperatures 

 of the sea, and of the nature of the bottom. Americans, English, 

 Germans, Norwegians, and Chilians have all added much to our 

 knowledge in this direction. 



The United States Coast Survey has done valuable work of this 

 kind in the Gulf of Mexico, where very numerous soundings and 

 temperature observations have been made to determine the contour 

 of the bottom and of isothermal surfaces. In addition, the work of 

 completing the hydrography of those portions of our coasts not yet 

 thoroughly examined, and of re-examiniug the localities liable to 

 change, has been diligently prosecuted. 



On the Atlantic coast surveying work has been done at Deer Isl- 

 and and Saco Bay, on the coast of Maine ; on the coast of New Jer- 

 sey, in Delaware Bay, in Albemarle and Pamlico Sounds, on the 

 coasts of South Carolina, Georgia, and Florida, and on the Florida 

 Reefs. 



On the Gulf coast extensive work has been done on the coasts of 

 Florida and Louisiana, including observations of currents, volume 

 of discharge, differences of level, changes of depth, etc., at the 

 mouths and bars of the Mississippi River. 



On the Pacific coast the survey of the coast-line of Northern and 

 Southern California, as well as that of Oregon and Puget's Sound, 

 has been carried on. 



In the prosecution of these surveys nineteen parties have been en- 

 gaged on board of the same number of small vessels, nine of this 

 number being steamers and the rest sailing-vessels. 



The work of compiling a " Coast Pilot," or sailing directions for 

 the Atlantic coast, has also steadily progressed. 



The United States Hydrographic Office has continued the routine 

 work of exchanging hydrographic information with foreign hydro- 

 graphic offices, and of publishing, promptly all notices which might 

 be of use to our mercantile and naval marine. From the hydro- 

 graphic offices of England, France, Germany, Italy, Russia, Spain, 

 Austria, Denmark, Sweden, Portugal, Holland, Brazil, and Chili, in- 

 formation as to dangers discovered, or as to the establishment of 

 aids to navigation, has been constantly received, translated, and ex- 

 amined, while to these governments, as well as to chambers of com- 

 merce, marine insurance offices, and prominent newspapers at the 



