president's address. 29 



chromosplieric envelopes, and are belched foi'tli in fountains to 

 hundreds of thousands of miles beyond the sun's surface ; these 

 jets are often seen by aid of the spectroscope in the neighbourhood 

 of sun spots when near the edge of the sun's disc, and are tlie 

 cause of the red protuberances seen around the edge of the daik 

 moon during a total eclipse, on which occasions, so long as totality 

 lasts, a beautiful phenomenon known as the corona is also seen, 

 which it is generally supposed is composed of matter in a 

 comparatively cool state, either in the process of being ejected 

 from or falling back upon the sun's surface. 



The red protubei'ances, as the jets of hot hydrogen seen during 

 total eclipses were named, used to be considered phenomena only 

 to be seen during total eclipses until it was shown by Jansen and 

 Lockyer at the Indian eclipses of 1872 that they could be seen at 

 any time when present by means of a properly arranged spectro- 

 scope. The possibility of seeing the corona also at times other 

 than that of total eclipse or, in fact, almost at any time, has 

 more recently suggested itself to some astronomers, and Dr. 

 Huggins has by a photographic method obtained results that are 

 very important, and seem to show that the faint light from the 

 heated matter which produces the phenomenon of the corona 

 seen during total eclipses of the sun, is capable of acting on the 

 sensitive silver tilm and giving a picture. 



Dr. Huggins found that by "stopping off" or filtering the 

 bright glare from the sun itself that a photographic impression 

 could be obtained of the surrounding region, and in almost every 

 plate a faint picture, apparently of a coi'ona, was obtained. A 

 good deal of doubt was expressed as to the pictures being real 

 impressions of the corona, but a photogi'aph secured at nearly 

 the same time that a total eclipse was observed in another part 

 of the world afforded an opportunity for comparison, and it was 

 found that the photograph corresponded very closely with 

 drawings and photographs taken during the progress of the total 

 eclipse. 



Of Mercury and Venus — the two planets nearest the sun — we 

 know little that was not known a hundred years ago, and although 

 statements have from time to time appeared of discoveries of 

 markings, signs of mountains, and so forth, they have not been 

 such as could be accepted by astronomers. It is generally con- 

 sidered they both possess somewhat dense atmospheres, but their 

 rotation periods even are, as yet, a mystery. 



No heavenly body has been so thoroughly watched and 

 scrutinised as our satellite the moon, its geography, or rather 

 selenography, has been most minutely examined and beautiful 

 maps constructed. Now and then we have heard of certain 

 minute changes in the surface having been observed, or of 

 appearances as of an active volcano, or jets of steam, but I think 

 it is now generally conceded that the lunar surface is in a stage 

 of unchangeableness, if one may use such a word. 



