Intelligence andMiscellaneous Articles. 235 



After catching a few spectra in different directions, I at length 

 decided on keeping the direct-vision prism pointed a little to the 

 west of Leo Major, with the axis of the prism parallel to the horizon. 

 The spectra which I saw were those of meteors which started from 

 the radiant-point and passed through the belt of Orion. Of course 

 the number of meteors which came into my field was comparatively 

 limited ; but the whole of them travelled in a direction parallel to the 

 axis of the prism, a condition essential in the observation of the 

 spectra. 



From the rapid flight of the meteors rendering the spectra very 

 difficult to catch, I cannot pretend to speak with confidence of the 

 appearance of the spectra shown by the prism ; but I saw a great 

 difference between the spectra. I believe that I saw spectra of the 

 following kinds : — 



A. Continuous spectra, or those in which the whole of the colours 

 of the solar spectrum were visible excepting the violet rays. 



B. Spectra in which the yellow greatly preponderated, but which 

 ia every other respect resembled those above described. 



C. Spectra of almost purely homogeneous yellow light, but with 

 a faint continuous spectrum-— that is, a faint trace of red on one side 

 and green on the opposite side of the yellow portion of the spectrum. 



D. Spectra of purely homogeneous green light ; of this kind I 

 only saw two. 



I observed through the prism spectra of several trains. The light, 

 which was mostly blue, green, or steel-grey, generally appeared ho- 

 mogeneous ; but this may have arisen from the light having been too 

 faint to produce a visible spectrum. Stars below the second or third 

 magnitude, although visible through the prism, fail from this cause 

 to give spectra in which blue and red are perceptible. 



It will probably be remarked that I have not spoken of having 

 observed any lines in the spectra. All the nuclei seemed to give 

 continuous spectra which contained the whole of the colours of the 

 spectrum ; what I should term the tails, not the trains, of the nuclei 

 presented the appearances I have described. In every instance I 

 remarked that orange-yellow appeared to preponderate over the 

 other colours in the continuous spectra. When a prism only is used, 

 it seems to me impossible that any sharply-defined lines should be 

 shown. Still, from differences in the colours of spectra, some infor- 

 mation may, I think, be obtained. As is well known, chemists and 

 mineralogists infer the presence of certain elements in the substance 

 under analysis from the colour communicated by the substance to 

 the blowpipe-flame. Thus, if the flame become yellow, they suspect 

 the presence of sodium ; red, strontium ; green, barium or thallium ; 

 lavender, potassium. The prism will do more than this ; it will show 

 if the flame contains even a faint trace of any other colour, while 

 without the prism the faint colour would be completely masked by 

 the colour which predominates. From the difficulty of catching 

 meteors within such a narrow space, I fear it will be found impossible 

 to use a prism provided with a slit formed by a pair of knife-edges 

 so as to define any lines. But I think it may be possible to use a 



