RECENT ADVANCES IN SOLAR ASTRONOMY. 27 



This theory falls in well with the facts established by Spoerer re- 

 specting the motion of the sun-spot zones, and the general, though 

 slow, poleward movement of sun-spots. 



Per contra, we have to note that Mr. Lockyer, in his recent lectures 

 on solar physics, reported in " Nature," appears to be ready to accept 

 the old theory that the spots, and their accompanying rings of promi- 

 nences, are " splashes," due to the fall of meteoric matter upon the 

 sun. He maintains that the spots appear first, and after them the 

 faculse and prominences ; unless the writer is much mistaken, how- 

 ever, the reverse occurs sometimes, and even frequently — first faculse 

 and then spots -among the faculse. 



The question of sun-spots and the weather is still debated with 

 about the same vigor as ever ; but, on the whole, there seems to be 

 no reason to modify the opinions expressed in the text. "While it 

 is not at all unlikely that careful and continued investigation will re- 

 sult in establishing some real influence of sun-spots upon terrestrial 

 meteorology, it is now also practically certain that this influence, if it 

 exists at all, is extremely insignificant, and so masked and veiled as to 

 be very difficult to determine. There is no ground or reason for the 

 current speculations of certain newspaper writers who ascribe almost 

 every great storm in the eastern part of the United States to some 

 sun-spot or other. 



The strange connection between solar disturbances and magnetic 

 disturbances on the earth has, however, become more certain, if pos- 

 sible, than ever before, and is no longer anywhere disputed. In No- 

 vember, 1882, there was a very remarkable instance of an intense mag- 

 netic storm and polar aurora, simultaneous over all the earth, and 

 coincident with the sudden outbreak of an enormous group of sun- 

 spots. 



Mr. Lockyer announces, as the result of a long series of observa- 

 tions upon sun-spot spectra, that there is a striking difference between 

 the spot-spectra at the time of maximum and minimum sun-spot fre- 

 quency ; the lines that are most conspicuous by widening and darken- 

 ing are by no means the same in the two cases. The most remarkable 

 change is in the lines of iron, which are usually conspicuous, but almost 

 vanish from the spot-spectrum at the sun-spot maximum. 



The writer also has ascertained a curious and probably an impor- 

 tant fact with reference to the structure of the spot-spectrum. Under 

 extremely high dispersion it is found that the spectrum of the nucleus 

 of a spot is not continuous, but is made up of countless fine, dark 

 lines, for the most part touching or slightly overlapping, but leaving 

 here and there unoccupied intervals which look like (and may be) 

 bright lines. Each dark line is spindle-shaped — i. e., thicker in the 

 middle where the spectrum is darkest and tapers to a fine, faint, hair- 

 like mark at each end ; most of them can be traced across the penum- 

 bra-spectrum, and even out upon the general surface of the sun. The 



