10 Art. l.-T. Terada: 



above. The above discrepancies are quite systematic in character 

 and cannot be generally accounted for by the local topography 

 within a small extent. The last comparison of the two oceans, 

 suggests a considerable influence of the continent l.ying far beyond 

 tlie limit of the 10° circle here adopted for the determination of K. 



3. The very unsatisfactory results of the above attempt to 

 account for the variety of «i by the simple consideration of the 

 "continentality", led us to consider the matter more closely under 

 the light of some elementary theoretical considerations.'^ 



Take first of all, for simplicity's sake, only the two-dimensional 

 problem, in which the earth's surface considered as plane is taken 

 for the :ry-plane, and the isobaric as well as the isothermal lines are 

 all straight and parallel to the y-axis. Supjiose now the isobaric 

 surface originally plane at the heiglit z, Ije swelled up by C(^» ^) on 

 account of the heating of tlie underlying strata. The horizontal 



pressure gradient at the level z will Ije Qi» '^^- . If we may assume 



the steady state soon established, this will be equilibriated by the 

 friction, i.e. 



where u is the horizontal velocity toAvard x and /^ the coefficient of 

 friction.'^ Now, C may be roughly given ]:)y 



wliere 6 is (he mean absolute temperature at z and assumed in- 

 dependent of X, and d is the variable part of the temperature which 

 is to be considered as a function of both x and z, and also of time L 

 The above holds only on the assumption tliat the air columns are 

 kept b}^ vertical partition walls from expanding horizontally: l»ut 



1.) Prof, Okatla kiuilly dr.w our attention to a paper by Hill, Met. Zs, 5, 1888. p. 340, on 

 the annual variation of barouiotri«.' pressure in ludiii, in wliicli a similar idea as fallowed in 

 this section can be traced. 



2.1 The influence of the rotation of earth is here provisionally put out of account. The 

 effect will be referred to l.iti r. 



