32 K. HONDA, T. TERADA, Y. YOSHIDA, AND D. ISITAXI. 



nected system. Three modes of oscillation are possible : (a) the 

 first and gravest mode is the oscillation of the system as a 

 whole, (b) the second is that of seiches between the Bay and the 

 Sea, and (c) the last the oscillation of the Bay only. 



The calculated periods corresponding to these modes of oscil- 

 lation are respectively 363", 278™ and 217"\ Though long periods 

 obtained from observation fall near the calculated values, it is 

 difficult to decide, from the scanty data, whether the observed 

 periods actually correspond to the modes of oscillations above 

 referred to. 



(22) Shionomisaki (July 29-Aug. 7, 1903). PI. XIX, Fig. 

 3 ; PI. XX, Fig. 1-3. 



Shionomisaki is the foremost promontory of Kii, where a 

 light- house is placed. The observation was made at a beach 

 below the light-house ; the secondary undulation is very incon- 

 spicuous, but we can sometimes trace the undulation of tlie 

 periods 11.3"-16.3^ 25.8'" and 34.1'^ 



In a small bay of Kushimoto, whicli is not far from the 

 promontory, Kelvin's tide-gange is constantly working. It is 

 remarkable to observe that while tlie secondary undulation at 

 the promontory is inconspicuous, the undulation in the bay is 

 very conspicuous. The periods 11.6™-13.0-, 16.5" -18 6™, 21 5'"- 23.7"^ 

 and 32.1™ are observed with considerable amplitudes, especially 

 in connection with the cyclones (PL XX, Fig. 2-3). The cal- 

 culated periods 12.8™ and 18.3™ fairly coincide with the observed. 

 The tide-gauge frequently recorded the sea waves originated on 

 the American coast of the Pacific. 



The periods observed in the case of a cyclone or of sea 

 waves are the same as those observed in ordinary case. 



(23) Bay of Osaka (Aug. 2-1 5, 1902). Top. 43. PI. XXI-XXV. 



