182 [June, 1842. 



the evidence which the recent accounts from the West Indies 

 furnish, of the general correctness of the hypothesis, originally 

 advanced by Michell, in the Philosophical Transactions for 

 1760, that the movement of the earth in earthquakes is undu- 

 latory. That such is the nature of the motion may be con- 

 sidered indeed as established, both from observation in many 

 regions of the globe, and from instrumental investigations 

 now in progress in Scotland. Professor Rogers proposes to 

 explain the billowy oscillation of the ground, by actual waves 

 engendered on the surface of the great fluid lava-mass, sup- 

 posed to occupy the whole interior of the globe ; and he ac- 

 counts for the waves, by the sudden or explosive escape of 

 highly compressed vapours, by the rending of the crust, or 

 through other outlets. 



He suggested to the Society the importance of procuring, 

 through correspondence on the part of members, some more 

 detailed and accurate statements than have yet appeared in the 

 public prints, in relation to the phenomena of the late shocks 

 in the West Indies ; as regards, 



First. The extent of the earthquake ; whether it reached 

 the mainland of South America, and to what distance north- 

 ward from Porto Rico and St. Domingo it was felt at sea. 



Secondly. The direction of the undulations and accompa- 

 nying concussions. 



Thirdly. The precise time at each locality of the occur- 

 rence of the first shock, and of each principal succeeding one. 



Fourthly. Whether the cloud of vapour reported to have 

 been seen at Port Plate, on the north-east coast of St. Domin- 

 go, was actually such, or merely dust, caused by disturbance 

 of the soil or the crushing of falling buildings. 



