112 Messrs. K. Honda, T. Terada, and D. Isitani on the 
The results o£ calculation of two corrections for three bays 
are given below : — 
Bay 
4/V^ ; 
Corr. for section. 
Corr. for mouth. T. 
213"' 
97-5 
39-5 
600 
4-24-8 m 
+ 8-5 
-10-7 
-16-8 
+46-5 1 " 

+ 8-6 
15-8 
284 m 
106 
36-4 
59-0 
Of'unafco 
Tsuruga 
According to our investigation, the bay of Aomori oscil- 
lates in two different modes with the periods 295 m and 103 m . 
The longer period corresponds to the fundamental oscillation; 
while the shorter one corresponds to the lateral oscillation, 
for which the mouth correction is naturally zero. The last 
two bays in the above table are good examples, showing that 
the correction due to the section and that due to the mouth 
nearly cancel each other. Similar remarks apply for many 
other bays. 
When the mouth of a bay is decidedly contracted, formula 
(1) or (3) fails to give the period of oscillation, in which 
case formula (5) is to be used. The bay of Osaka, which is 
almost surrounded by land and which communicates with 
the external sea through two necks, Akashiseto and Yura- 
seto, may be taken as an example of such bays. 
For the resultant conductivity of necks, the sum of 
separate conductivities was duly taken. The data for the 
calculation of the period estimated from the chart is : — 
Akashiseto ... ^ = 3*9 km., Z 1 =6*2 km., 7^ = 41 m., 
Yuraseto ft 2 = 5'0km., £ 2 = l'2km., 7< 2 = 27m., 
S = T47 Xl0 3 kin. 2 , \=150km. ; 
whence by formula (5), T = 270 m . This agrees nearly with 
the largest period observed, 260 m — 310 m . 
In the following table are given the periods calculated by 
formula (1) for all observed bays *. The periods corrected 
for the variation of the section and for the mouth are given 
in heavy type. The letter S indicates that the periods which 
it follows are those for the lateral or seiche-like oscillation 
in the bays. In the table only the observed periods, that we 
* In the table, 1-5 are the bays along the coast of Hokkaido, 6-9 
those along the coast of Japan Sea, 10-25 those along the southern 
coast of Honshiu, 26 that in fehikoku, and 27-29 those along the coast of 
Kiushiu. Futami is a small bay in Bonin Island (Ogasawara), and Kiirun 
the sole harbour in Formosa. 
