SECONDARY UNDULATIONS OF OCEANIC TIDES. 41 



(2) Tei (July 23— Aug. 3, 1903). PI. XXXIII. 



This station is situated on the Pacific coast of Tosa. The 

 records show undulations of tlie periods 7.5"\ 25.9", 30. ß'"- 

 32.9"\ 39.9"\ 49.r^-52.9'" and 73.9'"-77.5"\ small in amplitude 

 and short in duration. 



On July 30 to 31, the sea was very rough notwitlistand- 

 ing calm weather, when a remarkably simple secondary undula- 

 tion of considerable amplitude appeared, lasting over 12 liours 

 with a mean period of 51'". The appearance of this remark- 

 able undulation is probably connected with the low atmospheric 

 pressure then prevailing over the vicinity of Formosa (PI. XCIII). 



(3) Susaki (Aug. 9-28, 1903 and Aug. 20-Sept. 7, 1904). 

 Top 45. PL XXXIV-XXXVII ; PI. XXXVIII, Fig. 1-2. 



Susaki is a deep bay on the middle coast of Tosa. The 

 observations were made at 5 stations Yamasakibana , Shiraiwa, 

 Otani, Heshima and Kure. The diagrams of Yamasakibana 

 are characterized liy simplicity of undulation, the periods ob- 

 served are 30.9", 35.4"- 38.5", 39.9-41.6", 43.1 "-46.8" and 50.0"^ 

 -54.0". 



As an illustration of the modes of superpositions of a 

 series of different waves, rectified diagrams are given in PI. 

 XXXV, A. B. C. In curve A, a train of waves of the period 

 38™ is superposed on waves of the period 7G"\ the former com- 

 ponent being most conspicuous between he, wliile the latter is 

 pronounced between ah. In curve B, the waves of the period 

 76™ are superposed on the waves of the period 38™ between 

 ah, the latter component gradually passing into the waves of 

 36™ between he. In curve C, between ah, waves of the periods 

 51™ and 35'" form an apparent beat, and between he, waves of 

 100'" are superposed on waves of 50™, 



