Beam of November 17, 1882. 335 



is an example) describe courses along parallels of magnetic 

 latitude ; and hence he does not consider its course to have 

 been a meteor-one. 



Another divergent point is the rate of motion. The " beam " 

 had, as the result of the observations I have recorded and in 

 Prof. Herschel's opinion, a rate of some 10 miles per second ; 

 while in Guillemin's Le Ciel, p. 235, we find the information 

 that the rate of flight of bolides is considered to be 70 to 175 

 kilometres (40 to 130 English miles) per second. 



A third, and to my mind the strongest, objection to the Pro- 

 fessor's theory is the well-known spectrum of the aurora. This 

 spectrum is unique of its kind, and has been long since disso- 

 ciated from that of the zodiacal light (which light Prof. Grrone- 

 man connects with aurorse and with the cosmic theory), Prof. 

 Piazzi Smyth and Pingle having incontestably proved the 

 latter to be a continuous one without any bright lines what- 

 ever. Nor does the auroral spectrum at all resemble that of 

 meteors or bolides. The last, according to Konkoly, consists 

 of rays (bright lines) of iron and other metals (probably nickel, 

 cobalt, and manganese, J.R. C). The aurora-spectrum does not 

 give the idea of a metallic spectrum (with a possible exception 

 of the red and citron lines), but rather that of a gaseous cha- 

 racter ; and certainly a positive coincidence of the red and 

 citron lines with any known metal line is far from being 

 proved. Prof. Groneman has indeed quoted me in his Theorie 

 Cosmigue (p. 13) as, in Phil. Mag. ser. 4, vol. xlix. p. 249 

 (should be 265), remarking on an " exact concordance " be- 

 tween the iron and aurora spectra. But this is certainly going 

 further than I intended ; for my expression, " close coinci- 

 dences," is too strongly rendered by " concordance exacted 

 If, too, the plate of spectra accompanying that paper be ex- 

 amined, the state of the matter in fact stands thus as to coin- 

 cidences, thus: — 



W.L. Aurora lines. W.L. Iron lines. 



6297, the red line Not compared. 



5569, the citron line 5571, one of three close 



5390, in blue 5370 [together. 



5233, do 5231 



5189, do 5192 



feoK d ° X no comparable 



4f 29* I ^° a k an( * f nnes * 



I have also very considerably qualified any such remark as 

 that above alluded to by pointing out (' Aurorse,' pp. 118-170) 

 that the connexion between the two spectra, though it might be 

 suspected, cannot be considered as proved, the fine iron lines 



2B2 



