METEOROLOGY. 331 



the sea than over the land, owing to the feeble uprising carrcnt, as it 

 is also lower over the slightly' heated lands of high latitudes and over 

 the hind during the night as compared with the day time.] 



252. Dr. A. Sprung, of Hamburg, in reference to the daily period in 

 the direction of the wind which has for centuries been recognized, says 

 that the theory of vertical ascending currents or topsy turvey move- 

 ments would lead us to the following conclusions which are fully ex- 

 planatory of this periodicity : 



1. In the northern hemisphere, on the low plains and on high plains, 

 the wind has a tendency to change its direction with the hands of a 

 watch in the morning and against the hands in the afternoon. 



2. In the northern hemisphere on the summits of mountains a simi- 

 lar oscillation in the direction of the wind will occur, but in the opjio- 

 site direction. 



3. In the southern hemisphere the oscillation at low stations will be 

 against the hands of a watch in the morning and with them in the 

 afternoon, or oi)i)Osed to the rule for the low lands, and agreeing with 

 the rule for the mountain summits in the northern hemisphere. 



4. In the southern hemisphere for mountain summits the oscillation 

 is opposite to that of the low lands of that hemisphere. 



5. At the equator the wind direction is not affected. 



G. On the ocean, where the daily period in the strength of the wind 

 is slight in consequence both of the slight vertical diminution of fric- 

 tion and of the slight ■warming of the ocean surface, this oscillation in 

 direction is also not sensible. 



So far as observations are at hand the above conclusions seem to be 

 confirmed, and so strong is the deflection due to uprising currents thus 

 theoretically explained that the diurnal change of wind at most north- 

 ern stations consequent on the eastward movement of storm centers 

 whose paths lie north of the station is alunst entirely annulled by it 

 in the afternoon, whereas in the morning the two forces combine to ex- 

 aggerate the phenomenon. (Z>. M. Z., i, pp. 15-05.) 



253. Dr. A. Sjuning gives an elementary geometrical derivation, which 

 is more complete than that given by Zoppritz ami Buff, of the deflection 

 due to the earth's rotation. {B. M. Z., i, p. 250.) 



254. Wm. M. Davis, of Harvard College, gives an elementary proof 

 of the deflection, due to the earth's rotation, of bodies moving par- 

 allel to its suriace, showing the three general princii)les ui)on which, 

 he sajs. Professor Ferrel bases his formula for this deflecting force; this 

 is reproduced by Uanu with a few notes from Van Nostrand's Engineer- 

 ing Magazine. {Z. 0. G. il/., xviii, p. 299.) 



255. Dr. F. Ivoth, of Buxtehude, comments upon Professor Davis' pre- 

 sentation of the subject to the effect that it does not make clear the 

 point under dis])ute between himself and Dr. Sprung; he, however, 

 recognizes that Professor Davis's method of demonstration virtually 

 .assumes that the earth is a sphere, and that the true or apparent force 



