SECONDARY UNDULATIONS OF OCEANIC TIDES. 45 



corresponding to the binoclal oscillation of the bay is very con- 

 spicuous while in the third curve, the periods of fundamental 

 oscillation only are observable. 



(2) Aburatsu (Dec. 27-31, 1904). Top. 58. PI. XLI. 

 Aburatsu is a small bay on the southern coast of Hiuga ; 

 simultaneous observations were made at Alniratsu and Umega- 

 hama, inside and outside the bay respectively. In the bay, 

 we observed conspicuous undulations, though they are not reg- 

 ular. The periods observed are 15.0'"- 19.0'", 21.ry"- 24.5'", 

 37.5"- 39.2™ and 43.0"; they are nearly the same as those ob- 

 served at Hososhima. In ordinary weather, the amplitude of 

 the conspicuous undulation often exceeds 13 cm. The calculated 

 period is 15.1"\ 



Outside the bay, the undulations are very inconspicuous ; 

 but the same periods as those inside arc also traceable. If we 

 bring two corresponding records in and outside the bay into 

 coincidence, we can distinctly trace the corresponding undula- 

 tions of one record in the other (PI. XLI, Fig. 1 and 3, or 2 and 

 4). As in the case of Hososhima, if we bring two records of 

 any consecutive days into coincidence as regards the tidal phase, 

 we notice the same succession of secondary undulations. 



(3) Kagoshima (Aug. 1-7, 1905). Top. 59. PI. XLII-XLIII. 

 The large Bay of Kagoshima has an elongated form, 77 km. 

 long and 20 km. broad in its widest part. The island of Sakura- 

 jima, an active volcano, situated about 11km. from its end, 

 divides the bay into two portions communicating with each 

 other by two channels on both sides of the island. The ob- 

 servation stations were Kajiki, Kagoshima and Ibusuki ; they are 

 situated at the end, along one of the channels and at about 

 10 km. from the mouth of the bay respectively. The first and 



