59 



attributed the similarity of spectra to the white surface reflect- 

 ing proportionately the sky-light and all its peculiarities, and 

 judged that if the spectroscope were brought within a few feet 

 of the Avail the lines would remain the same. I tried tbem 

 with a Avhite wall and found that the absorption lines disappear 

 almost completely at an interval of three or four feet. When 

 20 feet oif 1 noticed a nearly similar spectrum to that of the sky. 

 On another occasion with a white disc I got most lines up to 

 within a few inches of tlie slit. Thus one part of the sky 

 might indicate by absorption bands in its spectrum a condition 

 that Avas only the reflection by this portion of sky of absorp- 

 tion that occurred elscAvhere. 



The observations of equally eminent men show that tlie 

 rainband is often seen at glow times : — i. At an early period of 

 the glow, EUery stated that the spectroscope indicated excess of 

 moisture. 2. The reports from Magdeburg state that in the 

 spectrum of the gloAv uncommonly strong rainbands Avere seen. 

 3. Professor M. Smith, of Madras, stated that a great amount 

 of watery vapour Avas indicated as being in the air. 4. J. F. 

 Donnelly had variations of absorption during one observation. 

 He found in place of the rainband shading off from D towards^ 

 E, a broad band shading off' towards a. In a short time this 

 band iiearly disappeared, and a became prominent, shading off 

 botli Avays, &c. 



Upon consideration it appears that if the vapour were low 

 down Ave might get rainbands, whilst if the vapour Avere high 

 lip witb dry air lower doAvn Ave might get dry air spectrum. 

 And conditions could exist so that we might get both dry air 

 and vapour bands. This is important, and in the report by J. 

 H. Poole this case actually exists. In reference to the examin- 

 ation during Pebruary with one of BroAving's micro-spectro- 

 scopes and comparing the results with, spectrum measured in 

 wave lengths, he finds in connection with the variable telluric- 

 lines absorption both by dry air and vapour. Thus there Avas 

 nearly total obscuration of violet end of spectrum, dark green 

 very faint, red end very brilliant, little a just visible, B 

 broadened to a thick black stroke, and c enveloped in an aqueous 

 vapour band. Between c and D, about 63, Avas a dry air band 

 very sharp, but the principal dry air band Avas between 57 and 

 58. On the immediate side of D nearest to c was a vapour 

 band. My own examination with the spectroscope shows that 

 in the majority of cases Avhere there is a glow the rainband is 

 somewhat prominent during the early part, Ioav down, fre- 

 quently disappearing rapidly towards the latter end of the 

 glow. 



The existence of a halo or corona round the sun, the relations 

 it bears to the gloAV, its inconstant character, and its intimate 



