48 K. HONDA, T. TER ADA, Y. YOSHIDA, AND D. ISITANI. 



experiment with the model gave also fairly coincident values. 



(5) Fukahori. Top. 60. PL XL VI. 



Fukahori lies near the western mouth of the bay of Naga- 

 saki ; here Kelvin's tide-gauge is always working. The undula- 

 tion is generally inconspicuous ; the same periods as those 

 observable at Nagasaki are also traceable. It is interesting to 

 notice that though the ordinary oscillation of the bay is very 

 prominent at Nagasaki, it is not conspicuous at Fukahori, the 

 latter being situated at the node of the oscillation. Even the 

 great ahiki of Nagasaki on May 2, 1905 (PI. XLVI, Fig. 1-2) 

 was only 30 cm. in amplitude at Fukahori. On the other 

 hand, the seiches between Nagasaki and Fukahori are rather 

 conspicuous at the latter station, where the oscillation forms 

 its loop. Fig. 1 and 2 are two records, when large ahikis 

 appeared at Nagasaki ; Fig. 3 is an example of the record in 

 stormy weather. 



VI. BONIN ISLANDS AND FORMOSA. 



(1) Futami. Top. 04. PI. XLVII. 



Since December, 1900, a tide-gauge of our system has 

 been set up in the bay of Futami in Bonin Islands (Ogasawa- 

 rajima) about a thousand kilometers south off the coast of 

 Honshiu. The undulation in tlie bay is always very regular 

 and conspicuous, with periods 15.3'"- 16.5", 17.2"^ and 18.0" - 21.2 \ 

 indicating that in this portion of the far ocean, there always 

 exist waves of moderately long periods with greater or less 

 amplitude. The period calculated is 13.0'" which is somewhat 

 less than the observed vahie. 



(2) Kelung. Top. 05. PL XL VIII, Fig. 1-2. 



Kelung is a harbour at the northern end of Formosa ; here 

 Kelvin's tide-gauge has been set up since ten years ago. The 



