Prismatic Spectra of the August Meteors. 165 



like lightning, burst overhead, leaving a streak from 6 Cygni, 

 half- way to a Lyra, for twenty seconds. A cloud unfortunately 

 dimmed the streak. In the spectroscope, as far as cloud 

 would permit any judgment of the streak to be formed, its 

 aspect was the same as to the unassisted eye. The light of the 

 streak was therefore probably homogeneous, and the streak itself 

 probably a luminous gas. 



No. 4; Ih. 15m. a.m. About equal to a second mag. star. 

 Shot in three- quarters of a second, from Cassiopeia half- 

 way to o Honorum, and then turned round the quarter of a 

 circle, to u Honorum, where it vanished, leaving a streak for 

 half a second on its course. In the spectroscope the general 

 appearance of the meteor, and of the streak in the field of 

 view, was the same as that of the purely reflected image by 

 the side ; the conclusion being, as before, that the light, both 

 of the meteor and of the streak, was homogeneous, or that the 

 luminous substance of the meteor was a gas. 



No. 5 ; lh. 40m. a.m. About equal to a second mag. 

 star. Passed slowly through a short path near /3 Tauri, 

 directed from Cassiopeia? ; duration, one second ; leaving a 

 streak at the place for three seconds. The spectrum of the 

 meteor and streak was quite equally diffused over a space 

 about \° in width ; its colour greyish white ; the diffuse train- 

 spectrum vanished without further change, the conclusion 

 being that in this case the train might, like the nucleus, be com- 

 posed of heated sparks. 



No. 6; 2h. 15m. a.m. Equal to a first mag. star. Shot 

 on the same course as No. 2 ; duration, one second ; leaving a 

 bright streak for four seconds. The spectroscope was turned 

 towards the streak before it disappeared. The train was 

 widened by the prisms to a greyish-white band, somewhat 

 greater than a quarter of a degree in breadth. It faded from 

 sight without further change ; the conclusion in this case also 

 being, that the train might possibly be composed of heated sparks. 



Three spectra in the foregoing observations appeared homo- 

 geneous, like that of a luminous gas (Nos. 2, 3, 4) ; and three 

 were continuous, or diffuse (Nos. 1, 5, 6), like that of an 

 ordinary spark. The question, accordingly, whether luminous 

 meteors might or might not contain solid substance, remained 

 undecided, when daylight beginning to appear, put a stop to 

 further observations. 



The following night, observations could fortunately be 

 resumed, and the perplexing appearance of the meteor spectra 

 on the previous night, received a truly surprising and most 

 satisfactory explanation, in the repeated appearance in the 

 spectra of the streaks of a yellow line, unmistakably that of the 

 metal sodium- in combustion. 



