PHENOMENA MANIFESTED IN TELEGRAPHIC LINES DURING THE 

 GREAT AURORA BOREALIS OF FEBRUARY 4, 1872 ; AND THE 

 ORIGIN OF NORTHERN LIGHTS. 



By Professor G. B. Donati, 

 Superintendent of the Astronomical Observatory at Florence. 



[Translated from the Italian for the Sniithsouian Institution from the Rivista Scien- 



tifico-Industriale.] 



It is not necessary for me to give a description of the luminous phe- 

 nomena manifested daring the great aurora of the 4th of February last. 

 So many descriptions of these have been published, that it is very easy 

 for any one to obtain information on the subject. But it will not be 

 unnecessary for scientific purposes to make known the results derived 

 from the observations which during that exhibition of northern lights 

 were made in the various telegraphic offices of this kingdom, and to 

 compare those observations with others made contemporaneously beyond 

 Italy. In doing this I am indebted to the favor of Mr. Commendator 

 D'Amico, director- general of the Italian telegraphic lines, who furnished 

 me with all the observations made by his subordinates on that occa- 

 sion. From the aggregate of those observations, the following conclu- 

 sions, I think, may safely be drawn : 



The fitful currents and the corresponding perturbations manifested 

 along the telegraphic lines, on the occa.sion of the aurora of February 4, 

 were greater on the lines extending from east to w^est than on those ex- 

 tending from north to south. This was the case even when the lines 

 running from east to west were much shorter than those from north to 

 south. In fact, Inspector-General Masi, who was at the office of Bag- 

 nara, Calabria, from his accurate observations concludes that the line 

 from Bagnara to Naples, which runs almost entirely along the meridian, 

 and which is the longest of all the lines that meet at Bagnara, gave by 

 the needle of the galvanometer the least deviation of all other lines. 

 And that, on the other hand, the line from Bagnara to St. Euphemia, al- 

 though shorter, but running almost exactly from east to west, showed 

 the influence of the aurora more than any other line. The same conclu- 

 sion is drawn from the observations made in Sardinia. On the lines 

 from Cagliari to Iglesias, and from Santa Teresa to Isola Madalena, 

 both very short lines and running from east to west, the perturbations 

 were greater than on the long lines froni Santa Teresa to Cagliari, both 

 the latter lines running from north to south. This fact had been noticed 



