44 K. HONDA, T. TEEADA, Y. YOSHIDA, AND D. ISITANI. 



recorded several sea waves, which were oriofinated on the 

 American coasts and traversed across the Pacific. Simultaneous 

 observations were made at Hososhima and Isegahama situated 

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

 regular undulations appeared superposed on the tidal waves ; the 

 periods varied from 17.8'" to 20.3™ according to the tidal phase. 

 In calm weather, the amplitude of undulation amounted even to 

 25 cm. The period of the undulation slightly decreases, as the 

 tide passes from low water to high. The calculated period is 

 19.0", which fairly agrees with the observed one. The change 

 of the period caused by the change of the depth by tidal motion 

 has also the range, which is to be expected from the theory. 

 Besides, longer periods 34.0"- 38.7'" and 43.4'"- 49.1" are some- 

 times observed. 



Outside the bay, undulations of the periods 17.8"- 20.3'" are 

 very faint, and inconspicuous undulations of the longer periods 

 are also observable. Placing a record in the bay upon the 

 corresponding one of the open coast, we can distinctly trace 

 undulations in the two records, which correspond to each 

 other. 



On the open coast of Hososhima, we actually met with two 

 small inlets some ten meters long, each of which was constantly 

 excited by Avaves of short periods proceeding one after another 

 toward the inlets, and made an approximate standing oscillation 

 of considerable amphtude, having the node at its mouth. 



If we bring two records of any consecutive days into coin- 

 cidence as regards the tidal phase, we observe the same suc- 

 cession of undulations. 



PL XL, Fig. 1-3 are tlie records in stormy weather obtained 

 by Kelvin's tide-gauge. In the first two curves, the period 



