348 eCIENTIFIC RECORD FOR 1882. 



States naval officers who Lave measured differences of longitude tbrough 

 submarine cables from Madras, by way of Singapore, Hong-Kong, 

 Shanghai, and Nagasaki, to Wladiwostok in Siberia, connecting there 

 with the chain of measurements made from Pulkowa Observatory by 

 Eussian officers, andjoiningatthe Madras end to the Indian longitudes 

 also determined electrically from Greenwich by officers of the great 

 trigonometrical survey of India. 



So accurately is it now possible to perform work of this kind that the 

 great polygon from Greenwich by way of Suez, India, China, Japan, 

 Siberia, and Russia, back to Greenwich, closes with an error only of 

 thirty-nine one-hundredths of a second of time. 



HYDEOGEAPHT. 



In almost all parts of the world hydrographic surveys have been 

 progressing by the labors of officers of different nations, although the 

 year has witnessed neither the inception nor the completion of any great 

 undertaking. In considering the constant hydrographic work in prog- 

 ress on the shores of our own country, as well as others, it must be 

 borne in mind that from the nature of the work it must be piactically 

 interminable, for no sooner is a chart of a harbor or coast line published 

 than corrections are made necessary by the changes in the bottom, and 

 consequent depths of water, caused by the action of tidal and other cur- 

 rents, as well as by the never-ceasing elevations and depressions of the 

 shore line, which geologists tell us are all the time going on. 



On the coast of the United States the work has been prosecuted zeal- 

 ously by the officers of the United States Coast Survey, some of the more 

 important pieces of hydrographic work performed being, in Maine, the 

 survey of Dyer's and Gouldsborough bays ; in Massachusetts, the exam- 

 ination of Salem and Gloucester harbors and of Pollock Eip shoal ; in 

 New York, the resurvey of the lower bay of NewTork; an examina- 

 tion of changes in Delaware and Chesapeake bays ; a resurvey of Chin- 

 coteague shoals j a resurvey of Norfolk harbor; examination of shoals on 

 the coasts of North and South Carolina; a resurvey of Beaufort harbor; 

 continuation of the hydrographic survey of the east and west coasts of 

 Florida, including the bars of Saint George's sound and Pensacola har- 

 bor; a resurvey of Key West harbor, and a continuation nearly to com- 

 pletion of the coast of Texas. On the Pacific coast, the general hydro- 

 graphic survey of the Californian coast has been continued, as well as 

 a survey of bays, inlets, and ports in Puget Sound, and a reconnaissance 

 of the waters of Southern Alaska. 



The only imjiortant surveys executed under the orders of the Navy 

 Department have bieen on the west coast of Mexico, by Commander 

 Philip, in the U. S. S. Eanger, and a survey of the Bay of Samana,in the 

 island of Santo Domingo, by Commander Bridgeman in the U. S. S. 

 Despatch. Tbis survey embraced the Yuna and Barracouta Rivers as 



