Dove on the Law of Storms. 315 



Art. VIII. — On the Law of Storms ; by H. W. Dove.* 



[From PoggendorfF's Jlnnalen der Physik und Chemie, 1841.] 



That a considerable decrease of atmospheric pressure should 

 be an effect of any unusual disturbance of the atmosphere is a sup- 

 position so natural, that it at once occurred to those who first re- 

 marked that the weight of air surrounding us is not always the 

 same. For the purpose of measuring these changes, Otto von 

 Guerike attached a scale to the water barometer which he had 

 invented, and in the 21st chapter of the Mirabilia Magdeburgica, 

 in Schott's Technica Curiosa, he records the following remarka- 

 ble observation : — " In the year 1660 the air was once so uncom- 

 monly light, that the index pointed below the lowest mark on the 

 glass tube ; on seeing this, I said to the persons who were present, 

 that doubtless there was a great storm somewhere ; two hours 

 afterwards the tempest was raging in our district, though with 

 less violence than it had done over the ocean." To mention only 

 one more recent example, I may recall the storm of the 17th Jan- 

 uary, 1818, of which the ravages are still visible in the forests of 

 Prussian Lithuania, after the lapse of nearly a quarter of a century. 

 This storm extended from the coasts of England to Memel, and 

 was felt throughout a region of two hundred and forty German 

 miles in length, and forty-one German miles in breadth. On the 

 18th of January the barometer fell at Konigsberg eight lines in 

 eight hours. The whole fall between the 3rd and the 17th 

 of January was twenty-one lines. In Edinburgh the fall of 

 the barometer and the violence of the storm were also both re- 

 markable. 



The experience of the last two centuries has so far confirmed 

 the remark of Otto von Guerike, that the scales attached to our 

 common barometers usually terminate with " very stormy." But 

 its applicability is not confined to the temperate zone : in lat. 70° 

 N., Ion. 70° W., the warning afforded by a fall of 9"'.29 in the 

 marine barometer, enabled Scoresby to avoid the dangers of a 

 tempest which lasted two days uninterruptedly, and he conse- 

 quently strongly recommends the use of these instruments to 

 whalers when in high latitudes. In the regions of the trade 



* Taken from Part X. of Taylor's Scientific Memoirs, Vol. Ill, p. 197. 



