194 



ANNUAL REPORT SMITHSONIAN INSTITUTION, 1952 



tralia, and the southern tip of Africa. In the strait between Madagas- 

 car and the African coast the time of high water is 12 hours after 

 the transit and low water occurs 6 hours later. 



The ocean basins of the Pacific that definitely respond to the semi- 

 daily tide-producing forces of the moon are shown in figure 5. There 

 is a major basin that covers most of the Pacific Ocean area. A nar- 

 row second basin crosses the major basin. It extends from the Cali- 

 fornia coast to the Fiji Islands and New Zealand and thence to the 

 southern tip of South America. 



Figure 5. — Tidal basins in the Pacific Ocean. 



It will be noted that California and Lower California in Mexico 

 form a geographic end to this basin. The oscillation of the waters 

 tends to increase the height of the tide at this location. High water 

 occurs at the sixth hour after the moon's Greenwich passage. 



In the major basin, high water occurs along the shore of the Gulf 

 of Alaska on the ninth hour after the moon's Greenwich passage. 



Long series of tidal observations on the open coast of off-lying 

 islands have assisted in checking the geographical limits of the great 

 Pacific tidal basin and of the location of the nodal lines. One of the 

 latter touches the coast of Japan, at Aomori, where there is a small 

 range of tide. There are small ranges, iy 2 feet, nearAcapulco on the 



