SECONDARY UNDULATIONS OF OCEANIC TIDES. ö / 



compared with the tide on the Pacific coast of Shikokn. 



(25) Shimonoseki (Jan. 14-17, 1905). PI. XXVII, Fig. 2. 



As it is to be expected, the tidal cnrvc at Shimonoseki 

 has a pecnliar character, superposed by the secondary un- 

 dulations of short duration of the periods 4G.5"\ 54.o"-57.0'" 

 and 04.8'". \ye can also trace an undulation of longer period 

 of about 150'". 



IV. PACIFIC COASTS OF SHIKOKU. 



(1) Strait of Xanito (Aug. 1-25, 1900). Top. 43. PI. 

 XXVIII-XXXll. 



The Strait of X^aruto is famous for its rapid current and 

 the eddies accompanying it. The strait separates Harimanada 

 from tlie Pacific by a narrow neck about 1.1 km. wide. The 

 phase of the tide in the sea is just opposite to that of the 

 Pacific ; and when the Pacific is in the high water or in the 

 low water, the sea is in the low water or in the high water 

 respectively, so that at the strait, a level difference of 1 to 1.5 m. 

 is produced, and consequently a torrent of water rushes from 

 the ocean into the sea or in the reverse direction, according to 

 the tidal phase. When tlie current attains its maximum velo- 

 city, it often exceeds 10 knots per hour. The current is always 

 accompanied with roaring sound and eddies. Eddies are usually 

 formed behind the stream ; their diameter exceeds G meters, 

 and they have funnel-shaped surfaces. If a boat be drawn into 

 them, it is very difficult for it to get out. 



The observations were made at 5 stations — Shioyasumi, 

 Hinoura, Yebisujima Ogeura and Kameura, of which dif- 

 ferent pairs were simultaneously observed. The records at 

 Shioyasumi and Kameura give the tide on the Harimanada 



