334 EAKTHQUAKES. 



Locli Ness rose suddenly for the period of three quarters 

 of an hour.^ 



As another example of the disturbance of water at the 

 time of a great earthquake in districts where the earth- 

 quake was not felt, may be mentioned the swelling of the 

 waters of the Maraiion, in 1746, on the night when Callao 

 was overwhelmed. 



Sudden variations in the level of the water have been 

 many times observed in the North American lakes. The 

 changes in level which sometimes take place in the 

 Grenfer and Boden lakes are supposed to have some 

 relation to the condition of the atmosphere. A rising 

 and falling of especial note took place on April 18, 1855. 



In Switzerland these sudden changes are known as 

 * seiches ' or * rhussen.* 



From the observations and calculations of Prof. Forrel 

 it would seem that the period of the ' seiches ' depends 

 upon the dimensions of the lakes ; the calculated periods 

 dependent on the depths of the lakes being approximately 

 equal to the observed periods.^ 



W. T. Bingham, writing on the volcanoes of the 

 Hawaian Islands, remarks that it is not unusual for the sea 

 to be agitated by great and unusual tides, and that such 

 sea waves have not been attended with volcanic eruptions 

 or seismic disturbances. Thus in May 1819 the tide rose 

 and fell thirteen times. On November 7, 1837, there was 

 an ebb and flow of eight feet every twenty-eight minutes. 

 Again, on May 17, 1841, like phenomena, unaccompanied 

 by any other unusual occurrences, were recorded.^ 



Phenomena which may possibly hold a relationship to 

 earth pulsations are the periodical swellings of the ocean 

 on the coast of Peru. Dr. C. F. Winslow, who made a long 



» Annual Register, vol. iv. 1761, p. 92. 



2 Phil. Mag.y May 1876, p. 447. ^ Boston SiW. Nat. Hist., 1868. 



