THE 



AMERICAN JOURNAL OF SCIENCE 



[THIRD SERIES.] 



Art. XXXIII. — On the Deflection of the Plumb-line and 

 Variations of Gravity in the Hawaiian Islands; by E. D. 

 Preston, Sub- Assistant, U. S. Coast and G-eodetic Survey. 



[Published by permission of the Superintendent of the U. S. Coast and Geodetic 



Survey,] 



On the return of the Solar Eclipse Expedition from the 

 South Seas, in 1883, two of the party stopped in the Sand- 

 wich Islands for the purpose of determining the force of grav- 

 ity. An old pendulum station on the island of Maui, occupied 

 by DeFreycinet in 1819, was the point chosen. While there 

 the latitude of the place was determined with precision, by 

 the method of equal zenith distances. This latitude was car- 

 ried back by triangulation to Honolulu by Professor Alexan- 

 der, the Surveyor-General of the islands. It was there com- 

 pared with the local astronomical latitude as given by Captain 

 Tupman, of the British Transit of Venus Expedition of 1874. 

 Their comparison revealed a discrepancy, — quite incompatible 

 with the accuracy of the work, — as shown either by the star 

 observations at the terminal points, or by the triangulation 

 connecting them. This seemed to prove, as indeed had long 

 been suspected by Professor Alexander, that there were un- 

 usual plumb-line deflections. Both the excess of matter in the 

 high mountain masses above, and the defect of matter in the 

 deep sea below, would indicate this. 



Am. Jour. Scl— Third Series, Vol. XXXVI, No. 215.— Nov., 1888. 

 20 



