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production of Earthquakes. Each assigns a different cause, it 

 is true, for the motion of the fluid, but both causes exist, and 

 must exist together. If there be a tidal movement of the fluid 

 interior, as M. Perrey appears to have established, there may 

 also be a centrifugal movement ; each may be capable of break- 

 ing the solid crust of the globe, or, in other words, of causing 

 Earthquakes. Mr. Stodder suggested, that the anomalies, which 

 M. Perrey found, were caused by the centrifugal force, and not 

 by the tidal force. 



Dr. Charles T. Jackson remarked, that if the sun and moon 

 exerted a tidal action upon the fluid matters of the interior of the 

 globe, as they do upon the ocean waters, that it ought to be mani- 

 fested by the rising and falling of the liquid lavas of volcanoes, 

 especially in those great volcanic openings in the Sandwich 

 Islands. If this were true, it would give more probability to M. 

 Perrey's hypothesis, as explained by Mr. Stodder. He would ask 

 Dr. Charles Pickering, who was familiar with these volcanoes, 

 whether, at Kilauea, or at any of the other craters in those vol- 

 canic islands, any regular periodicity was observable in the rising 

 and falling of the liquid lavas, and, if so, whether they corre- 

 spond to the times of the moon's phases ? 



Dr. Pickering replied that he was not aware of any regular 

 periods of elevation and subsidence of these lavas. He was 

 under the impression that they were quite irregular. 



Prof. William B. Rogers said, that he had been greatly inter- 

 ested in reading the Report of M. Perrey's researches, and was 

 pleased to see them brought to the attention of the Society. 

 Referring to the suggestion of Dr. Jackson, as to the value of 

 observations at Kilauea, in evidence of the tidal motion of the 

 fluid interior of the globe, he remarked, that while there was 

 much ingenuity in the idea of thus converting the insular vol- 

 canic mountain into a vast tide gauge for measuring the move- 

 ments of the fluid nucleus of the globe, we have no right to an- 

 ticipate any obvious correspondence between the fluctuations of 

 level in the liquid of the crater, and the tidal movements beneath 

 the earth's crust. Supposing a connection to exist, the channels 

 must be variable and tortuous, and often probably connected with 

 cavities containing gas and vapor, and having numerous and 



