SECONDARY UNDULATIONS OF OCEANIC TIDES. 23 



several nodal lines are conceivable, which may change continu- 

 ously from one to the other. The above value corresponds to 

 the mean position of the nodal lines, and tlierefore the calculated 

 values corresponding to the other nodal lines, may be greater or 

 less by several minutes than the above value. In the actual case, 

 we also found the periods varying continously from 5G.7"' to 

 62.9" or from 62.9"^ to 07. 7". 



(8) Tonoura. Top. 15. PI. VI, Fig. 4-5. 



Tonoura is a small inlet situated north of Hamada in 

 Iwami ; here a Kelvin's tide-gauge is at work. The secondary 

 undulation is conspicuous, especially in stormy weathers (PI. YI, 

 Fig. 4-5). The characteristic period in the bay is 11.9"-12.9" 

 while the calculated value is ll.F", in good accordance with 

 the actual. Besides, tlie periods 15.3'" and 21.5'"-2S.8" are 

 sometimes observed. 



In concluding the description regardmg Japan Sea coast, 

 it may be observed that in many of these stations, undulations 

 of the periods 120'"-! 30'" and 150'"-! 80'" may sometimes be traced. 



III. PACIFIC COASTS OF HONSHIU. 



(1) Same (Aug. 24-25, 1905). PI. YII, Fig. 1. 



Same is an open coast on the Pacific side of j\Iutsu ; here 

 the secondary undulation is conspicuous, but not regular. 

 The periods observed are 1G.4"\ 35.0'" and 41.5"\ 



(2) Miyako. Top. 16. PL VII, Fig. 2-3. 



Miyako is a bay on the coast of Rikucliiu, where a mete- 

 orological station is placed. Dr. A. Imamura has set up a tide- 

 gauge of the Richards' type at Kajigasaki, for the purpose of in- 

 vestigating sea waves in connection with the earthquake, and many 

 valuable records were obtained, some of which are reproduced in 



