A. MATHEMATICS AND ASTRONOMY. 31 



from east to west, from northeast to southwest, or from south- 

 east to northwest. Wochenschrift, 1873, 290. 



NATURE OF THE AURORA. 



Iii the valuable memoir of the lamented Donati on the 

 great aurora of February 4, 1872, there is given a brief synop- 

 sis of the views of various physicists on the nature of this 

 phenomenon, from which we quote the following: 



Des Cartes considered the aurora as a meteor falling from 

 the upper regions of the atmosphere. Halley attributed it 

 to the magnetism of the terrestrial globe, and Dalton agreed 

 with this opinion. Coates supposed that the aurora was de- 

 rived from the fermentation of matter emanating from the 

 earth. Mairan held it to be a consequence of a contact be- 

 tween the bright atmosphere of the sun and the atmosphere 

 of our planet. Euler 'imagined the aurora to proceed from 

 the vibrations of the ether among the particles of the terres- 

 trial atmosphere. Canton and Franklin considered the auro- 

 ra as a purely electrical phenomenon. Parrot attributed the 

 aurora to the conflagration of carbureted hydrogen, escaping 

 from the earth in consequence of the putrefaction of vegeta- 

 ble substances, and considered the shooting-stars as the initial 

 cause of such conflagration. Oersted and De la Rive con- 

 sidered the aurora as an electro-magnetic phenomenon, but 

 purely terrestrial. Olmsted suspected that a certain nebulous 

 body revolved around the sun in a certain time, and that 

 when this bodv came into the neighborhood of the earth a 

 part of its gaseous material mixed with our atmosphere, and 

 that this was the origin of the phenomenon of the aurora. 

 The author having considered the appearance of the great 

 aurora of the 4th and 5th of February, 1872, as a fit occasion 

 to arrive at some correct conclusion in regard to the aurora, 

 and having, by means of circular letters, received from all 

 parts of the world a mass of valuable material, concludes 

 from the study of these observations that the luminous phe- 

 nomenon of the great aurora was observed over a vast extent 

 of the earth during the night of the 4th and 5th of February, 

 1872. It w r as seen first in the East, in China, and then suc- 

 cessively in countries to the westward, until it was finally 

 seen in America. These manifestations were not simultaneous 

 at all points of the earth, but there was a tendency to antici- 



