JOURNAL OF THE COLLEGE OF SCIENCE, IMPERIAL UNIVERSITY, 

 TOKYO, JAPAN, 



VOL. XXIV. 



Secondary Undulations of Oceanic Tides. 



By 



K. Honda, Binolniliahtslti, T. Terada, Iii(jahhsJii, 

 Y. Yoshida, lîiç/aJcmhi, and D. Isitani, TiigohisM. 



With 2 frontispiecei=i and Do pJafcs. 



§1. INTRODUCTION. 



The tidal curves obtained by self-recording tide-gauges are 

 often accompanied by peculiar zigzags or secondary undulations 

 of considerable amplitude. The zigzags are generally conspicu- 

 ous at a station situated in a bay or an estuary. Tliis fact 

 seems to have been noticed by many earlier observers. 



Without entering into these early matters of literature, let 

 us mention later valuable investigations on this subject. David 

 Milne'=' discussed tlie remarkable undulations of July, 1843, on 

 the coasts of Great Britain, and ascribed their origin to the 

 storm tlien prevailing at the district. Admiral Smythf referred 

 to a similar pheiiomenon at Mazzara, Sicily, where it had long 

 been termed Mirahia or Marroh]>lo. Sir George AiryJ studied 

 the phenomenon at Malta and believed that it was due to 



*) D. Älilne, On a remarkable oscillation of the sea observed at varions coasts of Great 

 Trilain, Trans. Roy. Soc. Edin., 1844. 



t) Admiral Smytb, Memoir descriptive of the resonrces, inhabitants and hydrography 

 of Sicily (London, 1824). 



I) G. Airy, On tides in Malta, Phil. Trans. Roy. Soc. London, 169, 1878. 



