20 T. Terada : 



Thus the coiTesponcling isohyets show a ' 'valley' ' along the central 

 axis of the main island. If this tendency is any thing real, the ex- 

 planation must be sought in the draining influence of the Pacific 

 mountain range lying on the wind side of this district, enhancing 

 the ascending air current and condensing abundant moisture on the 

 Pacific side. Moreover, it is interesting to notice that this parti- 

 cular position of tlie centre lies nearly at the centre of curvature of 

 the circular axial line of Honsiu, and hence the geometrical relation 

 of the different parts of the land with respect to the centre are 

 similar to each other. This may at least explain why the isohyets 

 in this case run nearly parallel to the land. On the contrary, when 

 the centre of depression lies on the Pacific as in Fig. 8, not only 

 the distance of, but the angle made by the coast line, with the 

 radius vector drawn from the centre varies widely for different re- 

 gions. This explains why the expectation in this case varies rapidly 

 along the coast line. Nevertheless some peculiarities of the M 

 districts similar to the above are suggested by the isohyets corres- 

 ponding to some more remote positions of the centre than those 

 shown in the above figures. These cases were, however, omitted 

 on account of their small weight, and may better be postponed for 

 a future research. 



Again, comparing the Pacific and the Japan Sea coasts, for 

 examples Figs. 7, 8 with 10, 13, or 4 with IG, the expectation 

 seems to be generally greater for the Pacific districts than for the 

 Japan Sea side, when the centre lies on the sea not far from the 

 district in question. This may probably be attributed to the differ- 

 ence of temperature of the extended water bodies over which the 

 wind comes. 



Thus far we have considered only the average distribution of 

 precipitation for different positions of the centre of depression. For 

 the actual cases, the influences of an accidental nature, i.e. of the 

 trivial local irregularities in topography, meteorogical conditions, 

 etc., may give rise to various discrepancies compared with the 

 average relations. Still it is not difficult to find a number of tj^pical 

 examples among the daily charts, which may well illustrate the 

 above general inference. A few of these examples are shown in 

 Figs 39 to 42. 



