EARTH PULSATIONS. 335 



period observation upon the coast of Peru, found ' the highest 

 tides to prevail at Callao and Paita in December and Jan- 

 uary,' and ' also a series of enormous waves or sea-swells 

 to be thrown from time to time upon the coast, varying 

 from twenty-four to twenty-seven hours in continuance, 

 accompanied by unusual height of the tide during the 

 same period.' During June and July the ocean was 

 unusually tranquil. These phenomena do not appear to 

 be connected with great atmospheric storms, nor do they 

 hold any relation to the prevailing wind. They increase 

 "with and accompany the swelling of the tides, and occur 

 generally, but not always, about full moon. 



Sometimes they break suddenly upon the coast. 

 ' They are annual and constant in their periodicity,^ 



The periodical swellings are most noticeable between 

 Tumbez 3° S.L. and the Chincha Islands 14° S.L. 



These oceanic phenomena synchronise with the 

 periodic intensity of earthquake phenomena in that part 

 of the globe, and these with tidal movements.^ 



Other phenomena possibly attributable to earth 

 pulsations. — If we assume that earth pulsations have 

 an existence, these many phenomena which are otherwise 

 difficult to understand meet with an explanation. The 

 curious effects which were produced in the springs at 

 Toplitz at the time of the Lisbon earthquake may have 

 been due to a pulse-like wave. The flow of the principal 

 spring was greatly increased. Before the increase it 

 became turbid and at one time stopped. Subsequently 

 it became clear and flowed as usual, but the water was 

 hotter and more strongly mineralised. Sudden changes 

 in the flow of underground waters which from time to 

 time are observed may be attributed to like causes. 

 Secondary earthquakes such as occurred after the Lisbon 

 » ' Notes on Tides at Tahiti,' &c., Am. Jour. Sci. 1866, vol. xlii. p. 45. 



