Beam of November 17, 1882. 337 



Two other recent matters in connexion with the aurora- 

 spectrum seem to claim an attention before concluding this 

 paper. The first is communicated to ( Knowledge ' by Mr. 

 Cory, of Buckhurst Hill (before mentioned). In a letter to 

 that journal (vol. iii. no. 62), dated 30th of November last, 

 after describing the spectrum of the beam, he says : — " Upon 

 a previous occasion, when observing the aurora of October 2, 

 I noticed a bright line in a similar position, and for a few 

 minutes only three distinct bright lines in the red end of the 

 spectrum" [the italics are mine]. In a letter to me subse- 

 quently, Mr. Cory states he is sure of the lines (in a Browning 

 miniature spectroscope), though he could not give their exact 

 positions — facts which he repeated in a personal interview, 

 adding that by the red end of the spectrum he meant the 

 region on the less-refrangible side of the D lines. Prof. Stokes, 

 in the 'Arctic Manual/ 1875 (p. 26), says " and there are also 

 one or more lines in the red in red auroras." I am not aware 

 of the authorities upon which this statement is made. Although 

 varying W.L. positions have been assigned by different ob- 

 servers to the red line, I have hitherto assumed them to refer to 

 the same line, and did not think more than one had been seen. 



With Mr. Cory's uncertainty of positions, it is not easy to 

 make much of his observation; but a circumstance to be noted 

 in connexion with it is, that the single red line generally 

 remarked falls within a group of nitrogen lines, and it would 

 be interesting if the additional lines were found to do so too. 



The other matter to be referred to is the recent procuring of 

 an "Artificial Aurora" (as it has been not very happily called) 

 by Prof. Lemstrom, a name long known in auroral researches. 



At present our information on the subject is somewhat 

 meagre. In ' Nature ' (vol. xxvii. p. 322) we find that a tele- 

 gram, dated December ] 1th last, had been received by the 

 Finnish Academy of Science from Professor Lemstrom, as 

 chief of the Finnish Meteorological Observatory at Sodankyla. 

 This stated that, having placed a battery with conductors 

 covering an area of 900 square metres on the hill of Orantun- 

 turi, he found the cone to be generally surrounded by a halo 

 yellow- white in colour, which faintly but perfectly yielded the 

 spectrum of the aurora. This he considered formed a direct 

 proof of the electrical action of the aurora, and opened a new 

 field in the study of the physical condition of the earth. 



A further telegram stated that experiments with the aurora, 

 made December 2 9th in Enare near Kakala on the hill of Picta- 

 rintunturi, confirmed the results of those at Orantunturi. On 

 that date a straight beam of aurora was seen over the galvanic 

 apparatus. It was also stated that, from the magnetic observa- 



