320 Dove on the Law of Storms. 



On the 25th December, at 10 a. m. — 23 lines at Middleburg ; 

 21 at Gosport : 20J at Haarlem ; 18 at London : 17 at Helston ; 

 16 at Dieppe, Gottingen and Bremen ; 15 in Paris, Strasburg and 

 Bergen ; 14 at Heidelberg, Gotha and Leipsic ; 13 at Zurich, 

 Augsburg, Vienna, Prague and Breslau; 12 J at Joyeuse and 

 Inspruck ; 11 £ at Cracow and Dantzic ; 11 at Padua; 9 J at Chris- 

 tiania ; 8 at Florence ; 7 at Tilsit ; 6 at Rome, Molfetta and 

 Abo ; 3 at Petersburg. 



On the 25th December, at 8 p. m. — 17 lines at London ; 16J at 

 Helston and Apenrade ; 16 at Haarlem and Bergen ; 15 at Bre- 

 men ; 14 at Dieppe, Gottingen and Dantzic ; 13 at Paris, Gotha, 

 Breslau and Christiania; 12 at Strasburg, Berlin and Cracow; 

 1 1 at Turin, Zurich and Augsburg ; 10 J at Padua ; 10 at Prague ; 

 9 at Tilsit ; 8 at Florence ; 7 at Molfetta ; 4 at Petersburg. 



According to the one view, — in which it is considered that the 

 atmospheric pressure at a given place being from some cause un- 

 usually diminished, an inflowing takes place from all sides, — 

 there will be equilibrium between the several particles on a line 

 in which the pressure is equally diminished, and the general 

 direction of the wind will be perpendicular to that line. Accord- 

 ing to the other view, — in which the complex phenomenon is 

 regarded as the consequence of a rotatory movement, — the gen- 

 eral direction of the wind will be that of the above named line 

 itself. Thus the two assumptions lead to two directions of the 

 wind at right angles to each other. We have therefore next to 

 inquire to which assumption the observations correspond. 



From the above mentioned observations, it follows that the 

 march of the minimum was from the French coast towards the 

 southwest point of Norway, or nearly from Brest to Cape Lin- 

 denaes. What was the direction of the wind at the different 

 stations in reference to this moving minimum ? Was the direc- 

 tion towards the minimum ? or was it tangential to circles having 

 the place of minimum as their common but constantly moving 

 centre ? This may be directly tested in the most simple man- 

 ner, by laying down on four maps the place of the minimum for 

 the four epochs, 6 p. m. 24th December, and 3 a. m., 10 a. m., and 

 8 p. m. 25th December, and then marking on these maps the 

 directions of the wind simultaneously observed at the several 

 stations. If the arrows on the maps are found to be tangents to 

 concentric circles, the actual existence of these circles may be 



