T. Terada : 31 



Japan Sea districts. The latter fact still shows the unerring effect 

 of the third factor. 



Hann remarks that on the northern side of the Alps, the rain 

 fall is most ahundant on the rear side of a harometric minimum. 

 This fact may prohahly be explained l>y the predominating influ- 

 ence of the hydrodynamical factor, since the effect of a great moun- 

 tain range is equivalent to the increase of the coefficient of friction. 

 That northern Germany, including Swinemiinde and Breslau, has 

 maximum rain fall on the rear side of a depression, may be under- 

 stood by the combined effect of the second and the third factors. 

 The case of Great Britain investigated l)y Mill, seems at first sight 

 iiTeconcilable with the above considerations, since the heaviest 

 rainfall area occurs on the left side of the track of the centre, con- 

 tradicting in most cases the influence of the third factor. But it 

 must be remembered that Mill's results refer to the "smear" in 

 which the rainfall on the front and rear sides of the centre are 

 supesposed. He states, indeed, that the heaviest rainfall occurs in 

 advance of the centre. The influence of the third factor combined 

 with that of the first one may in some cases shift the centre of the 

 smear to the left side of the track ; the front rain falling on the 

 eastern side of laud or mountain is abundant on the northern side 

 of the track, due to the third influence, wliilc the rear rain is 

 abundant on the southern side of the track, on the western side of 

 the land, or any orographic irregularity ; hence if due to the first 

 factor, the rear rain is less abundant than the front rain, the centre 

 of the smear will lie on the northern side of the track. This seems 

 to explain most cases given by ^till where the depressions proceed 

 toward E. In order to explain different cases in which the relation 

 is apparently not so simple as considered above, exact knowledge is 

 of course necessary of the thermal and topographical conditions of 

 the district concerned for each particular case. 



Finall}", it must be remarked, to avoid misunderstanding, that 

 the present discussions involve no essential novelty as a theory of 

 cyclonic rainfall, except emphasizing the importance of the hydro- 

 dynamical influence due to the difference of the coefficient of fric- 

 tion. The alcove may only be regarded as suggesting a way toward 



