42 K. HONDA, T. TERADA, Y. YOSHIDA AND D. ISITANI. 



When different rectified curves ai'c compared with one an- 

 other, the remarkable fact is revealed that almost identical 

 forms of waves occur very frequently during the course of suc- 

 cessive days. The examples of such a coincidence of wave- 

 form are given in PI. XXXVI, cui've D-J. It appears that 

 some particular form of waves is often repeated at the cor- 

 responding part of the tidal curve, for two consecutive days ; 

 this is shown in curve D and D', in which identical waves 

 occur in the same relation to the tidal phase. It also occurs 

 that the same train of waves is recognized at the low water 

 of one record and at high water of another, as shown in curve 

 E and E', or F and F'. When, however, different records, which 

 are several days apart, are compared, the same waves are found 

 apparently with no definite relation to the tidal phase as shown 

 in curves H and H'. Curves I and I' show an example in 

 which a train of wave occurs on different days in apparently 

 inverted form. In curve J', the direction of the time is inverted. 

 Curve K shows an example in which secondary waves of 

 shorter periods are very faint, whereas a long wave of about 

 100" is rather conspicuous. Curves L and L' which are the 

 rectified records of Yotsu, are given for comparison with K. 



At Shiraiwa, the sea is very calm, whereas the secondary 

 undulation of the period 31.0" (PI. XXXVIII, Fig. 1) is most 

 pronounced. The periods observed at Otani are 17.6"-18.2'\ 

 35.4" and 53.3", and those at Heshima are 24.6"-27.6'", 39.7" 

 and 55.1". At Kure, secondary undulation of the periods 15 0"- 

 16.3" and 61.3" are noticeable. 



Comparing the records of Kure and Yamasakibana on the 

 same days (PI. XXXVII, Fig. 3-4), it will be seen that while 

 the wave somewhat longer than 60" is common to both 



