378 Height of the Auroral Arch of March 20, 1865. 



the needles, in the direction of the magnetic meridian. It 

 appears not improbable that the arch was one segment of a 

 luminous stratified discharge. An interchange of electricity 



Kg. 1. Keguster of Greenwich Magnetometers. 



Hours of G. M. T., 1865, March 20th, p.m. 



— -— * 5h so 6h 3 7h 3 8h 30 9h 30 lOh-— . 



6h ?• 

 Hours of Gr 



7h 3"> 8h 30 9h So lOh- 

 M. T., 1865, March 20th, p.m. 



between the north and south hemispheres of the earth, in 

 the form of an escape of galvanic electricity from the borders 

 of the icy regions, was an explanation of the aurora originally 



