168 Prismatic Spectra of the August Meteors. 



long; and faded away without any further change. The 

 spectrum of the nucleus showed prismatic colours. 



No. 16; 2h. 16m. a.m. Equal to a second mag. star. 

 Shot from Cassiopeise to /3 Andromedas, in half a second, 

 leaving a streak for two seconds and a half. The meteor was 

 seen with the unassisted eye. The last-fading portion of the 

 streak was examined in the spectroscope, where it appeared 

 more widely diffused than when seen with the naked eye. Its 

 colour in the spectroscope was a dull greyish white. 



No. 17; 2h. 27m. a.m. Brighter than a first mag. 

 star. Shot from a Cassiopeias to o Honorum, leaving a streak 

 for two seconds and a half. The train- spectrum was a diffuse 

 greyish- white band, j° in width, not sensibly brighter in any 

 part ; and it so faded. The spectrum of the nucleus was 

 bright, — red, and green. 



Daylight at this time began to appear, and observations 

 were obliged to be discontinued; the streaks of the August 

 meteors might, however, already be plainly divided into two 

 classes. In the majority of cases, a bright yellow line, having 

 the unmistakable appearance of the sodium line, was clearly 

 visible in the spectrum. In a smaller number of cases the 

 spectrum was merely a diffuse and greyish light band, or 

 ordinary spectrum of weak intensity, resembling the spectrum 

 of the glowworm's light. It will be interesting to observe 

 this form of meteoric spectrum, should it be more common 

 among the " phosphorescent" streaks of the November meteors 

 than it was in August last ; when only five such purely ' ' phos- 

 phorescent" streaks were noticed, entirely free from sodium 

 light. 



The spectra of the meteor-nuclei were seen in a few cases 

 only with distinctness ; as they were in general overpowered 

 by the brightness of the sodium light, whenever that was 

 present. When the streaks were phosphorescent only, and 

 free from sodium light, the nuclei in general presented highly- 

 coloured spectra, like the spectrum of solid matter at a glowing 

 white heat, or like the spectrum of an ordinary gas flame con- 

 taining white-hot solid particles of carbon. A better night for 

 observing nucleus- spectra would be the 12th of December, 

 when meteors leaving no trains are plentiful ; and they are 

 for the most part very brilliant, radiating from some part of 

 the constellation Gemini. 



That which spectral examination of the August meteors 

 has most certainly brought to light, is the existence of an 

 extraordinary quantity of the vapour of sodium in their lumi- 

 nous streaks ; so that many of the streaks, especially the 

 most conspicuous, and the most slowly-fading amongst them, 

 consist of nothing else but soda flames for a great propor- 



