388 RECORD OF SCIENCE FOR 1887 AND 1888. 



nent taken positive toward the north, and O the horizontal component 

 taken as positive toward the east. 



V=C (1-3 cos2 d)f 



N=-GCcos^sin 6 , cp 



0=D [sin ^ (1-3 cos2 6) g-\-Q cos^ 6 . y] 



"In these expressions /, 9), g^ y are functions of the distance of the 

 point in question in the atmosphere above the earth's surface. They 

 depend also upon the condition of the atmosphere at its two boundary 

 surfaces (the concentric spherical surfaces above and below). At both 

 these two boundary surfaces the vertical component V, and therefore 

 also /, must disappear. Furthermore, cp^ g, y, must disappear at the 

 earth's surface if we assume that there the atmosphere adheres to it. 



" The function q) is zero for a certain definite altitude — that is to say, 

 at this altitude the meridional current changes its sign ; below it is di- 

 rected toward the south, but above it is directed toward the north. The 

 function g is everywhere negative ; the function y is everywhere posi- 

 tive, but always zero at the earth's surface. 



" The two constants O and D unfortunately do not admit of direct nu- 

 merical computation, and that for two reasons : First, the unknown 

 value of the friction constant for atmospheric currents enters into them. 

 Again, they contain the whole ditference in temperature between the 

 equator :iud tlie pole. But it is allowable to assume that only a certain 

 fractional part of tbis difference of temperature is the actual effective 

 cause of the currents, since in the higher strata the difference of tem- 

 perature is certainly considerably smaller. 



*'In other respects tlie above expressions give a clear picture of the 

 currents. The vertical current (V) is an ascending one from the equa- 

 tor up to 350 16' north and south latitudes, but thence to the poles it is 

 directed downwards. The meridional currents (N) are at the equator 

 and at the poles; they attain their greatest value at 45° latitude. 



" In consequence of the earth's rotation there arises the current O 

 along the circles of latitude, which consists of two branches, Oi depend- 

 ing on the function g, and O2 depending on the function ;/. Oi is, from 

 the equator to 35° 16' north and south latitudes, directed toward the 

 west; there this current changes its sign, and in the higher latitudes is 

 easterly. O2 represents a current directed toward the east; everywhere 

 at the earth's surface it is zero (corresponding to the value of the func- 

 tion y), but, on the other hand, at higher altitudes it attains a very 

 considerable value. Both the movements Oi and O2 along the small 

 circles of latitude disappear at the pole. Moreover, the current O2 is 

 zero at the equator, and attains its greatest value at the latitudes 

 540 44/ north and south. 



" We would especially call attention to the fact that these results de- 

 pend essentially upon the assumption as to the distribution of tempera- 

 ture. A change iu the location of the maximum of temperature (as 



