i88o.] 
The Aurora. 
379 
ship — sails, spars, and all — seemed to partake of the same 
ruddy hues. They were as if lighted up by some terrible 
conflagration. Taking all together— the howling, shrieking 
storm ; the noble ship plunging fearlessly beneath the 
crimson-crested waves ; the furious squalls of hail, snow, 
and sleet, drifting over the vessel, and falling to leeward in 
ruddy showers ; the mysterious balls of dearie fire resting 
on our mast-heads, yard-arms, &c.; and, above all, the 
awful sublimity of the heavens, through which coruscations 
of auroral light would shoot in spiral streaks, and with me- 
teoric brilliancy — there was presented a scene of grandeur 
surpassing the wildest dreams of fancy.” 
A very considerable portion of Mr. Capron’s work, and of 
the illustrative plates, is devoted to the subjedt of the 
Spedtrum of the Aurora as noted by different observers, and 
the various coincidences to be found between its bright lines 
and bands, and the lines and bands exhibited by the spedtra 
of other known substances. Amongst more recent observers 
Lemstrom and Vogel are disposed to the conclusion that the 
spedtrum of the Aurora agrees in the main with the spedtrum 
of the air as illuminated by the eledtric spark. Angstrom 
concludes that the Aurora has two spedtra, one of which 
gives the very bright greenish line always present in the 
Aurora, the other comprising the other and fainter lines. 
The very important work of Lord Lindsay, Backhouse, H. 
R. Prodter, and Schuster in this department of research is 
also mentioned. An observation by Lecoq de Boisbaudran, 
cited apropos of the ruddy streaks so often seen in Aurorae, 
that the red line in the spedtrum of phosphoretted hydrogen 
is increased in brilliancy by artificially cooling the flame, 
deserves careful attention. Summing up the evidence of the 
spedtroscope as to the nature of the Aurora, Mr. Capron 
concludes as follows : — “As the general result of spedtrum 
work on the Aurora up to the present time, we seem to have 
quite failed in finding any spedtrum which, as to position, 
intensity, and general charadter of lines, well coincides with 
that of the Aurora. Indeed, we may say we do not find any 
spedtrum so nearly allied to portions even of the Aurora 
spedtrum, as to lead us to conclude that we have discovered 
the true nature of one spedtrum of the Aurora (supposing 
it to comprise, as some consider, two or more). The whole 
subjedt may be charadterised as still a scientific mystery, 
which, however, we may hope some future observers, armed 
with spedtroscopes of large aperture and low dispersion, but 
with sufficient means of measurement of line positions, and 
possibly aided by photography, may help to solve,” 
