JO Art. 5. — T. Terada, M. Isiuioto and M. linamura : 



the barometric gradiet must be one uf the most important. If 

 such be the case, due consideration must be paid to this point, if 

 we are to attempt to compare the amount of precipitation on botli 

 sides of the land and thereby deduce some topographical relation 

 with respect to the barometric gradient. If this precaution is not 

 made, the difference l>etween the l)()th sides will be largely 

 determined by the side on which the amount is decidedl}^ larger. 

 Hence the deviation of the yearly percentage value from the mean, 

 i. e. 100, Avas divided by the mean anomaly. These quotients 

 (Table I.) were adopted for the final data to be used in the com- 

 parison with the barometric gradient. 



7. The barometric gradients of the different parts of Japan, 

 to be used fe)r the comparison with the precipitation may be 

 obtained in difïerent ways. Referring to the mean annual isobar 

 chart, the isobaric surface over the land is far from being nearly 

 plane, chiefly due to the protruding area of high pressure lying 

 along the axial line of the land. On account of the latter, the 

 actual gradients on both sides in different parts of Japan may 

 differ considerabl}^ from each other and may even have nearly 

 opposite directions. In the present investigation, however, we 

 will at first put the axial high out of consideration, which is in 

 all probability very shallow phenomena, brought out by tlie 

 reduction to sea level, and take the gradient obtained from tlie 

 coastal stations. The general procedure taken is as follows. For 

 the Northern Japan I II, foi* example, we choose four coastal 

 stations, say Akita, Kanazawa on the Japan Sea side and jMiyako, 

 Tyosi on the Pacific side, forming the angular points of a 

 quadrilateral, as nearly i"ectangular as possible, including the 

 region in question. The difference of the pressure on both sides 

 divided by the mean distance may be taken as the measure of the 

 gradient in the direction combining the centre of the (opposite 

 sides. ^-^ If the quadrilateral l)e nearly rectangular, we obtain thus 

 the two rectangular components of the gradient. The stations 

 chosen for the purpose are as follows (see Fig. 1) : 



1) In the case when the isoViaric surface is nearly plane, it will he plausible to take a 

 trianu;le for the determination of irradient. But in such a case as is here concerned, the 

 procedure uieutioned almve seems more advisal)le as o'ivini' a kind of mean gradient. 



