214 Wisconsin Academy of Sciences, Arts, and Letters. 



with nothing less than the great South Pacific ocean, a thousand 

 miles oii" shore, for sufficient space to create the tidal wave, whence 

 they propagate the same all over the world from east to west. 

 Some think it possible that there is a new impulse given in each 

 ocean, while others think that possibly the origin may be in the 

 Indian ocean. 



That these speculations are not all correct is evident from my 

 chart of co-tidal lines, which is based upon a collection of actual 

 facts from undoubted sources. One tide reaches the west coast of 

 Africa at the same moment of absolute time that another reaches 

 the east coast of Madagascar. These can by no means be the same 

 wave in any form, for, after reaching the respective coasts, a por- 

 tion of each moves southward, these meet near the Cape of 

 Grood Hope, unite, and move south as one wave. One tide arrives 

 on the west shore of Patagonia at the same time that another 

 reaches the east shore of the Falkland Islands. These move 

 south and three hours later unite near Cape Horn and go south 

 as one wave. These also are two entirely separate and distinct 

 tides coming from diflferent oceans and from opposite directions. 

 A still more remarkable tide is that which reaches the north end 

 of New Zealand from the northeast. This tide travels south be- 

 tween Austria and New Zealand, is met by a tide from the Indian 

 ocean south of Tasmania, is turned eastward and makes the detour 

 of New Zealand in time to pass the succeeding tide off the noith 

 end of the Islands. This wave is an important one, as it returns 

 just in time to reform the Pacific tide. The Society Islands, 

 where there is no perceptible tide, lie in the node' between the 

 ascending and descending tides. The solar tide of 5-6 inches 

 reported at Tahiti is occasioned by the shifting of the node of no 

 tide, and the time, three hours before and after noon and mid- 

 night, is occasioned by what is termed ^5rim2;?^ and lagging of the 

 lunar tides. 



The tide of the Indian ocean has its origin near the center of 

 that ocean, first moving decidedly north and east and then spread- 

 ing in a north and west direction. Owing to the great difference 

 in depth of this ocean and the consequent resistance, this tide is 

 subject to movements peculiar to itself. The Maldive islands are 



