333 REPORT— 1872. 



I had no object-glass to collect light, but I had more prisms to disperse it, 

 so that with me the rings were not so high as those observed by E-espighi, 

 because I had not so much light to work with ; but, such as they were, I saw 

 them better, because the continuous spectrum was more dispersed, and the 

 rings (the images of the corona) therefore did not overlap. Hence doubt- 

 less Eespighi missed the violet ring which I saw ; but both that and 1474 

 were very dim, while C shot out with marvellous brilliancy, and W was 

 absent. 



These observations thus tend to show, therefore, that instead of the element 

 the line of which corresponds with 1474 existing alone just above the pro- 

 minences, the hydrogen accompanies it to what may be termed a great height 

 above the more intensely heated lower levels of the chromosphere, including 

 the prominences, in which the lower vapours are thrown to a greater height. 

 With a spectroscope of small dispersion attached to the largest mirror of 

 smallest focus which I could obtain in England, the gaseous nature of the 

 spectrum, as indicated by its structure (that is, bands of light and darker 

 intervals as distinguished from a continuous spectrum properly so called), was 

 also rendered evident. 



Photographs and Structure of Corona. 



The photographic operations (part of the expense of which was borne by 

 Lord Lindsay) were most satisfactory, and the solar corona was photographed 

 to a greater height than it was observed by the spectroscope, and with details 

 which were not observed in the spectroscope. Mr. Davis was fortunate 

 enough to obtain five photographs of great perfection at Bekul, and Captain 

 Hogg obtained some at Jaffna ; but the latter lack in detail. The solar nature 

 of most, if not all, of the corona recorded on the plates is established by the 

 fact that the plates, taken in different places, and both at the beginning and 

 end of totality, closely resemble each other ; and much of the exterior 

 detailed structure is a continuation of that observed in the inner portion, 

 independently determined by the spectroscope to belong to the sun. 



This structui'e I was also enabled to observe in my 6|-inch equatorial, even 

 three minutes after totality was over ; and we may now say that we know all 

 about the corona, so far as the structtire of its lower brighter levels (that 

 portion, namely, which time out of mind has been observed both before and 

 after totality) is concerned. It may be defined as consisting of cool promi- 

 nences^ — that is to say, in this region of the corona we will find the same 

 appearances as in prominences, minus the brightness. We find the delicate 

 thread-like filaments M'hich all are now so famihar with in prominences ; 

 the cloudy light masses, the mottling, the nebulous structure, all are abso- 

 lutely produced in the corona ; and I may add that the fainter portion of the 

 ring, some 5' round the sun, reminded me forcibly in parts of the nebula of 

 Orion and that surrounding jj Argus, as depicted by Sir John Herschel in his 

 Cape observations. 



While both in the prism and the G^-inch equatorial the corona seemed to 

 form pretty regular rings round the dark moon, of diflferent heights, according 

 to the amount of light utilized by the instrument, on the pliotograi)hic 

 plates the corona (which, as I have before stated, exceeds the limits actuallj^ 

 seen in the instrument I have named) has very irregular {ignored hy the 

 sjjectrosco2)e), somewhat stellate poles — a fact perhaps connected with the 

 other fact, that the most active and most brilliant prominences rarely occur 

 there. 



