A. MATHEMATICS AND ASTRONOMY. 17 



he considers due to parallax, and thiis calculates the dis- 

 tance of the rays. From a number- of observations made by 

 himself and Dr. Reimann he finds that the direction of the 

 rays in the aurora of February 4 deviated from the magnetic 

 zenith by from 3 6' to 10 2'. He thus finds for the different 

 rays heights varying from 150 to 280 miles. 



PROOF OF THE GREAT DISTANCE OF THE AURORA FROM 



THE EARTH. 



Mr. Ii. A. Proctor calls attention to what he considers a 

 strange circumstance connected with the remarkable aurora 

 of February 4 of this year. He remarks that if it be the 

 fact, as stated, that the magnetic perturbations were experi- 

 enced at the same time in America and Europe, while the 

 chief luminous phenomena commenced six hours later in the 

 former, it would go to show that the region of auroral mani- 

 festations is exterior to the earth, since the aspect of the si- 

 dereal heavens is the same in the evening hours in Europe 

 and in corresponding latitudes in North America. It would 

 seem, in fact, as if the great auroral light phenomena were 

 witnessed in Europe and America when those regions of the 

 earth were severally turned toward a certain region of extra- 

 terrestrial space. 3 A : March 9, 1872, 205. 



SECCHI ON THE AURORA OF FEBRUARY 4, 1872. 



Father Secchi, of Rome, has published his observations of 

 the aurora of February 4. At first the aurora had the ap- 

 pearance of a broad, nebulous, phosphorescent band, which 

 moved parallel to itself in the direction of the meridian. 

 After passing the equator its aspect changed. The whole 

 heavens, except a small portion in the south, shone with a 

 purple light, which changed to a yellowish-green on the north- 

 ern side. The magnetic needle was greatly agitated, chang- 

 ing by more than a degree. The spectrum of the crown was 

 very vivid. Angstrom's ray (5560) was visible in every part 

 of the heavens. In the spectrum of the bright red column a 

 red ray was also seen, perhaps C. In the bright parts of the 

 arch larcje numbers of bright lines were seen. He remarks 

 also that, in general, the aurora is followed by a decided and 

 extensive change of weather, and seems to be connected with 

 great movements of the atmosphere. 



