ON THE EARTHQUAKE AND VOLCANIC PHENOMENA OF JAPAN. 137 



Near to the instrument at S on the west side the ground is covered with 

 green corn about one foot in height, while towards the S.E. there is a 

 strip of bare ground perhaps fifty yards wide and one Imndred yards in 

 length. The movement, which, however, is slight, is towards the area 

 most open to the sun. 



Neglecting this strip, then, there is very much more open ground on 

 the western than upon the eastern side of the station, and the movement 

 may be explained on the assumption that this side, because it loses the 

 most weight, rises relatively to the other (fig. 11). 



Fig. 11. 

 S. — Moves east from 6 a.m. to 3 p.m. 



Eomaba S 



■ 6 



IS 



!.5 n 



Near to O the ground is somewhat more open on the north side, and 

 it would appear that the motion was towards this side. Because the 

 movements are slight, they might equally well be explained as a com- 

 ponent of a south-eastern tilting due to greater relief of load upon the 

 S.E. side, whicli is more exposed than that in the opposite direction. 



Although a diagram may be modified by contraction following desic- 

 cation in the immediate vicinity of an instrument, this detailed examina- 

 tion of the observations in relation to the localities at which they were 



Fig. 12. 

 O. — Moves north from 9 A.M. to .5 P.M. 

 Zf 18 15 iZ 9 6 5 21 IS IS 12 S> 6 S 



made tends to the conclusion that diurnal waves are in part distortional 

 effects of the earth's surface due to unequal relief of load from various 

 areas by evaporation. When the movements have been absent or small, 

 the instruments have been, at stations on the solid rock, well protected by 

 trees or on an open plain. Many anomalies occur which still require an 

 explanation, the most remarkable perhaps being the smallness of the 

 motions at A, where the hypothesis requires that they should have been 

 pronounced. The intermittent character in the movement at R may pos- 

 sibly be connected with the deep cutting on its western side, which breaks 



