224 THE POPULAR SCIENCE MONTHLY. 



them in connection with solar I may even say stellar physics, for 

 evidence is augmenting in favor of the view that interstellar space is 

 not empty, but is filled with highly attenuated matter of a nature such 

 as may be put into our vacuum-tubes. Nor can the matter occupying 

 stellar space be said any longer to be beyond our reach for chemical 

 and physical test. The spectroscope has already thrown a flood of 

 light upon the chemical constitution and physical condition of the sun, 

 the stars, the comets, and the far-distant nebula?, which have yielded 

 spectroscopic photographs under the skillful management of Dr. Hug- 

 gins, and Dr. Draper, of New York. Armed with greatly improved 

 apparatus, the physical astronomer has been able to reap a rich harvest 

 of scientific information during the short periods of the last two solar 

 eclipses ; that of 1879, visible in America, and that of May last, ob- 

 served in Egypt by Lockyer, Schuster, and by Continental observers 

 of high standing. The result of this last eclipse expedition has been 

 summed up as follows : " Different temperature levels have been dis- 

 covered in the solar atmosphere ; the constitution of the corona has 

 now the possibility of being determined, and it is proved to shine with 

 its own light. A suspicion has been aroused once more as to the 

 existence of a lunar atmosphere, and the position of an important line 

 has been discovered. Hydrocarbons do not exist close to the sun, but 

 may in space between us and it." 



To me personally these reported results possess peculiar interest, 

 for in March last I ventured to bring before the Royal Society a spec- 

 ulation regarding the conservation of solar energy, which was based 

 upon the three following postulates, viz. : 



1. That aqueous vapor and carbon compounds are present in stellar 

 or interplanetary space. 



2. That these gaseous compounds are capable of being dissociated 

 by radiant solar energy while in a state of extreme attenuation. 



3. That the effect of solar rotation is to draw in dissociated vapors 

 upon the polar surfaces, and to eject them, after combustion has taken 

 place, back into space equatorially. 



It is therefore a matter of peculiar gratification to me that the re- 

 sults of observation here recorded give considerable support to that 

 speculation. The luminous equatorial extensions of the sun which the 

 American observations revealed in such a striking manned (with which 

 I was not acquainted when writing my paper) were absent in Egypt ; 

 but the outflowing equatorial streams I suppose to exist could only be 

 rendered visible by reflected sunlight, when mixed with dust produced 

 by exceptional solar disturbances or by electric discharge ; and the 

 occasional appearance of such luminous extensions would serve only to 

 disprove the hypothesis entertained by some, that they are divided 

 planetary matter, in which case their appearance should be permanent. 

 Professor Langley, of Pittsburg, has shown, by means of his bolometer, 

 that the solar actinic rays are absorbed chiefly in the solar instead of 



