47l! I'rof>. S. \>. Liveiir.: .ind .1. hrwar. 



the others hardly conic within the limits of piobablc error. The ray 

 ll'L'u .>eem- tin. strong in proportion to the other*, but the >treni;th (f 

 that at _'.'!'_' seem- to .-i.-rord with the si i viigt I) <>f the rorresj>oiiding 

 rav in the corona. It will In- >ccn tluit the rays we enumerate above 

 correspond approximately to the stronger rays in Sir N. Lockyer's 

 list.* Further mea.-iirc> of the wave-lengths of the faint Mm 

 needed before we can >ay detinitely whether or no we have in our 

 tubes a sulistance producing the coronal rays, or sonic of them. 



As to the auroral rays, we have not seen any ray in the sjiectrutH 

 of our tubes near A r)~>71'~>, the green auroral ray. We have ob-er\ed 

 two weak rays at A 4206 and A 4198 which may possibly, one or l>oth. 

 represent the auroral ray A 420. The very strong ray of argon. 

 X 4200*8, would make it probable that aigon was the origin of this 

 auroral ray, if the other, equally strong, argon rays in the same region 

 of the spectrum were not absent from the aurora. Nor have we 

 found in the spectrum of our tubes any line with the wave-length 

 3915, which is that of another strong auroral line. On the othei 

 hand it seems probable that the strong auroral line A .'!.">,; may be due 

 to the material which gives us the very remarkable pair of line^ it 

 about the place of N of the solar spectrum. A :{. r >87, which are very 

 strong in the .spectrum of the negative pole, but only faint in that of 

 the capillary part of our tubes. It may well be that the auroral dis- 

 charge is analogous to that about the negative pole. "We have also a 

 fairly strong rav at A .'5700, which may be compared to the remaining 

 strong ray observed in the aurora A 3700. This, however, is a ray 

 which is emitted from the capillary part of our tubes as well as from 

 the negative pole, and is. moreover, emitted by Bath gas, and may very 

 likely be a neon ray. 



We hope to pursue the investigation of this interesting sj>ectrum, 

 and if possible to sort out the rays which may be ascribed to sub- 

 stances such as neon and those which are due to one or more other 

 substances. The gas from Bath, even if primarily derived from the 

 atmosphere which is by no means sure seems to have undergone 

 some sifting which has affected the relative proportions of helium and 

 neon, and a more thorough comparison of its spectrum with that of 

 the residual atmospheric gases may probably lead to some disentangle- 

 ment of the rays which originate from different materials. The 

 arrangement of the rays in series.it' that could be done, would be a 

 step in the same direction. 



We are indebted to Mr. Kobert Lennox. F.C'.S., for the great help 

 he gave us in the complicated manipulation with liquid hydrogen 

 required to fill the spectral tubes, and to Mr. ,1. W. Heath, F.C> t" 

 kind assistant e. 



* ' Boy. Soc. Proc.,' vol. 66, j>. 191. 



