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



to 1 901) ; the number of bays and coasts observed amounts to 

 fifty one in all. 



The observation consisted firstly in finding the periods of 

 the undulations peculiar to each bay or coast, and secondly in 

 comparing the phases of the undulation in the different portions 

 of a bay by simultaneous observations. 



In' all cases, portable self-recording tide gauges were used. 



The research on tlie plia se relation was carried out only 

 for several typical bays. 



Fig. 1. 



§ 2. TIDE-GAUGES. 



The tide- l'auge used in our first 

 excursion of the summer vacation 

 of 1903 was that designed by 

 Assistant Professor S. Nakamura.'^' 



The tide-gauge is very simple 

 and portable ; Fig. 1 shows dia- 

 gramatically the principle of the 

 apparatus. A and B are cylin- 

 drical vessels of glass ; A is con- 

 nected to sea -water by a lead tube 

 K through the cock li,. A suit- 

 able quantity of mercury is put 

 in A and B, which communicate 

 wdth each other by a thick 

 caoutchouc tube 6^. By sucking 

 a caoutchouc tube //, water is 

 brought into the vessel A ; when 

 the vessel and the lead tube are 



S. Niikiinmra, Troc. Tokyo Matli.-Phys. See, 1, p. 123, 1902. 



