208 ROYAL SOCIETY OF CANADA 



My investigations have established more or less synchronous phenomena, 

 but how they are related is not yet fully determined. 



CONCLUSIONS. 



1. Microseisms are essentially due to meteorological phenomena, 

 that is, to barometric pressure and the accompanying gradients. 



2. That the amplitude of the microseisms is largely a function of 

 the steepness of the barometric gradient. 



3. That areas of low barometer with steep gradients, but west of 

 Ottawa have little effect in producing microseisms. 



4. That strong microseisms are almost invariably accompanied by 

 steep gradients in the Gulf, with the St. Lawrence valley, containing 

 the great Champlain fault, on a line of steep gradients. 



5. That a well-marked Low sweeping up the Atlantic coast from 

 Florida to Newfoundland is almost invariably accompanied by marked 

 microseisms. 



6. Microseisms are but slightl}-- if at all influenced by the movement 

 of Lows across the continent. 



7. That microseisms are not produced by local winds and frictional 

 excitation of the earth's surface. 



8. That microseisms represent movements in vast blocks of the 

 earth's crust covering thousands of square miles, and the period possibly 

 dependent on or modified by marked geological configuration. 



9. That microseisms once produced may continue for some time 

 when the immediate cause has passed. 



'To the above may be added that, as the microseisms are mainly 

 dependent on the action of the liow on the ocean, and as at Ottawa they 

 are) recorded after the Low passes, the reverse should be the case in 

 Europe, where the ocean is to the west and the Low passes over it before 

 reaching the continent. 



