RESULTS OF MARITIME GRAVITY RESEARCH, 



1923-32 



Bt Dr. F. a. VENING MEINESZ 

 Professor of Geodesy, University of Utrecht 



Plates 33, 34, 35, 36 



GENERAL STATEMENT 



This report has been made at the request of Prof. 

 W. Vaiighan, for inchi.sion in his report on the status 

 of oceanographic research. 



The following expeditions have been made by the 

 writer for determining gravity at sea : 



1923, from Holland via Suez to Java o/b Hr. Ms. Subm. 

 K II 



1925, from Holland to Alexandria, o/b Hr. Ms. Subm. 

 KXI 



1926, from Holland to Java via Panama, o/b Hr. Ms. 

 Subm. K XIII 



1928, from Washington to the West Indies, o/b U. S. 



Subm. S 21 

 1929/30, three expeditions in the East Indies, o/b Hr. 



Ms. Subm. K XIII 



1931, research in the North Sea o/b Hr. Ms. O 13 



1932, e.xpedition in the West Indies o/b U. S. Subm. 

 S48 



1932, expedition in the Atlantic o/b Hr. Ms. Subm. O 13 



The expeditions o/b Dutch submarines have been 

 made for the Netherlands Geodetic Commi.ssion, 

 the expedition o/b the U. S. Subm. S 21, where the 

 writer was cooperating with Dr. Fred E. Wright 

 and Elmer B. Collins, for the Carnegie Institution 

 of Washington and that o/b the U. S. Subm. S 48, 

 during which the writer was assi.sted by Dr. Harry 

 Hess and by Mr. Townsend T. Brown, for the 

 International Expedition to the Bahamas under the 

 Directorship of Dr. Richard M. Field. 



The observations have been made by means of the 

 multiple pendulum method, which is described and 

 discussed at length in "Theory and Practice of 

 Pendulum Observations at Sea," by the writer 

 (published by the Netherlands Geodetic Commi.s- 

 sion, Waltman, Delft) and which is likewise treated 

 of in the publication of the U. S. Naval Ob.servatory 

 of the Expedition of the U. S. S. S-21. 



In 1931 the Italian Navy has organized an expedi- 

 tion in the Western part of the Mediterranean; 



Prof. Gino Cassinis took the direction of the 

 gravimetric research. The results of this expedition 

 are not yet available. 



Most of the results of these expeditions are 

 represented on the three accompanying maps, one 

 map giving the results of the expeditions of 1923, 

 1925, and 1926 between Holland and the Indies, 

 another containing the gravity data found in the 

 Netherlands East Indies and adjoining parts and 

 the third representing the results for the West 

 Indies found in 1926, 1928, and 1932 supplemented 

 by a great many values on land determined by the 

 U. S. Coast and Geodetic Survey. 



The maps contain the gravity anomalies in 

 milligal, i.e., the observed values after isostatic 

 reduction according to the system of Hayford- 

 Bowie,' minus the value for normal gravity as it is 

 given by the formula of Cassinis : 

 = 978.049 (1 + 0.0052884 sin=<^- 0.0000059 sin^ 2<t>) 

 The study of these results reveals two remarkable 

 rules that appear to be fairly generally valid. These 

 rules are: 



1°. The positive anomalies seem inclined to occur 



in fields, while the negative anomalies are 



mostly occurring in strips; the positive 



fields coincide often with deep basins: 



2°. The anomaly shows a tendency to increase, in 



a positive sense, when going from shallow 



water towards deep water; this seems to 



occur as well for continental coasts as for 



island coasts. 



Instances of the second rule are found at the 



Atlantic end of the English Channel, near the 



Azores, near the southeast coast of Spain, near Suez, 



near Sokotra, near the Maldive Islands, near the 



south coast of Ceylon, at the Atlantic side of the 



'The isostatic reduction of the results has been made at 

 the Bureau of the U. S. Coast and Geodetic Survey. 



61 



