SHORT MEMOIRS ON METEOROLOGICAL SUBJECTS 4G1 



the barometer is low and the temperature relatively bigh. If we now 

 go farther toward the west, tbe pressure of tbe air diminishes con- 

 stantly, but no change takes place in the direction of the wind. Gradu- 

 ally^, however, the pressure of the air begins to rise, wliile the wind 

 shifts round more to the west and grows somewhat colder. During a 

 constantly rising atmospheric pressure, the wind passes through the 

 west, and becomes a cold, rainy, northwest wind. If we continue our 

 progress toward the west, the pressure of the atmosphere rises still 

 higher, the wind shifts round more to the north, the air becomes clear, 

 and we come at last, under a constantly rising atmospheric pressure, 

 through a northerly wind into the next northeasterly polar current. If 

 we move in the contrary direction, *. e., from west to east, these phe- 

 nomena will, of course, be reversed. What I have desired hereby U 

 show is, that if we travel from cast to west, when everything is in a 

 normal state, we shall see the direction of the wind gradually change 

 in the manner stated by Professor Dove in his well-known law of rota- 

 tion, according to which the wind most frequently turns in a direction 

 with the sun, and that by traveling in an opposite direction, from west 

 to east, we shall see the direction of the wind change according to the 

 opposite law. Now, since Dove's law of rotation has been confirmed, in 

 the main, by the observations which have been made in various conn, 

 tries,* one is led to assume that the atmosphere has a movement some- 

 times from west to east, and sometimes from east to west around the 

 earth, which seems in itself to be quite probable, but one is led, at the 

 same time, to the conclusion that the easterly movement is the pre- 

 ponderant one. That this, moreover, is really the case, 1 hope the fol- 

 lowing will plainly show. From what I have said in the foregoing, it is 

 evident that if the moving masses of air which are conveyed from the 

 lower to the higher degrees of latitude by the equatorial air-currents 

 were of the same magnitude as the masses of air which are carried back 

 by the polar air-currents from the higher to the lower degrees of lati- 

 tude — which would, of course, necessarily be the case if the air from the 

 lower to the higher degrees of latitude did not bring with it moisture, 

 which is thrown off on the way — then, for each separate degree of lati- 

 tude, it would be necessary that the sum of all the pressures which the 

 force of the earth's rotation would exert upon the masses of air impelled 

 toward the poles from west to east should be equal to the sum of all 

 the pressures which the same force would exert from east to west upon 

 the masses of air w^hich moved from the pole toward the equator. In 

 such a case, taking all things together, there would have to be an equi- 

 librium between the forces which would respectively move the atmos- 

 phere iu an easterly and westerly direction. The case is, however, 

 different in reality, since the mass of air which moves toward the poles 

 brings with it a considerable quantity of aqueous vapors, in consequence 

 of which the mass of air which rushes toward the poles is always con- 



* See Professor Holten's paper in tbe Videaskabens Selskab Oversigt for 1S65, p. 113. 



