The U. S. Coast and Geodetic Survey 



7 



WORK DONE BY THE SURVEY 



What the Survey has accomplished in 

 the 70 3'ears of its active existence may 

 be broadly stated as follows : 



It has carefully mapped about 30,000 

 miles of topography and sounded out 

 minutely nearly 300,000 square miles of 

 water, while its deep-sea soundings 

 cover a little less than a million square 

 miles. The results of this work are 

 shown on about 500 charts of unrivaled 

 accuracy and beauty. But it must not 

 be forgotten that its energies have been 

 largelj' devoted to resurveys required 

 by the constantly shifting bottoms of 

 our southern shores. Bearing this fact 

 in mind, it may be stated that is has 

 completed a first survey of the Atlantic, 

 Gulf, and Pacific coasts of the United 

 States. It has observed tides at thou- 

 sands of stations, and publishes annually 

 in advance predictions not only for our 

 own coasts, but for all the ports of the 

 world to which our shipping is likely to 

 go. It has covered an area of between 

 three hundred thousand and four hun- 

 dred thousand square miles with its net- 

 work of triangulation, and has incident- 

 ally completed the measurement of an 

 arc of the parallel traversing our country 

 from ocean to ocean, and has measured 

 an oblique arc extending from Maine to 

 Louisiana. 



It has run many thousand miles of 

 precise levels. 



It has determined transatlantic longi- 

 tudes and covered the country with a 

 homogeneous system of astronomically 

 determined points. It has taken an 

 active part in the delimitation of na- 

 tional and state boundaries. 



It has undertaken the study of the 

 law of the earth's magnetism, and made 

 observations for determining the decli- 

 nation, dip, and intensit)' at many sta- 

 tions throughout our domain. 



It has published and maintains Coast 

 Pilot volumes of the Atlantic and Pacific 

 coasts and parts of Alaska. 



In regard to the present activity of the 

 Survey , a few words will prove of interest. 

 The completion of the transcontinental 

 triangulation and that of the oblique arc 

 has rendered it possible to adopt a single 

 system of geographic coordinates for all 

 points in this country which have been 

 trigonometrically determined, and the 

 office is engaged in the great and useful 

 task of making the computations and 

 preparing them for publication. Coop- 

 eration between the Take Survey and 

 the Coast Survey has resulted in the 

 adoption by the former of the same sys- 

 tem, and the necessary computations to 

 bring about this unification have been 

 made. At the same time, a comprehen- 

 sive investigation of the deflections of 

 the plumb-line throughout the area cov- 

 ered by the triangulation is in progress, 

 and one of its immediate results will be 

 to guide the Survey in making future 

 gravity researches. 



A few years ago Congress authorized, 

 by increased appropriation and legisla- 

 tion, the extension of the magnetic sur- 

 vey of the country. Magnetic observa- 

 tories, equipped with the most modern 

 and economical appliances, are being 

 maintained — one in Maryland, one in 

 Kansas, one at Sitka, Alaska, and one 

 in Hawaii. These observatories, at the 

 formal request of the German govern- 

 ment, are cooperating, in common with 

 others under foreign governments, with 

 the German and British South Polar 

 Expeditions by making simultaneous 

 observations. At the American observ- 

 atories the magnetic instruments record 

 photographically day and night the 

 changes of the magnetic forces. Rapid 

 progress has been made in the accumu- 

 lation of magnetic data, their discussion, 

 and publication. Meridian lines to aid 

 surveyors are being established at or 

 near county seats of the several states. 

 There has just been issued a comprehen- 

 sive volume of declination tables and 

 isogonic charts. 



As a member of the International 



