May 15, 1884] 



NA TURE 



59 



isobars, the following approximate errors of the aneroid 

 have been determined for the lowest recorded readings: — 



S.30 

 9 



Aneroid, 



inches 

 27-300 

 27'200 

 27-155 

 27-200 

 27-300 



Approxi 



Mean error 



-0-230 

 -0-240 



-0230 



If the correction + 0-230 inch -for instrumental error and 

 height be applied to 27-155 inches, the lowest observed 

 sea-level reading at Kilcreggan was only 27-385 inches — a 

 reading, it may be remarked, agreeing closely with the 

 lowest readings noted at several stations on the mainland 

 and islands of Argyllshire earlier in the evening. The 

 Ochtertyre reading, 27-332, was thus, so far as known, 

 absolutely the lowest recorded during the great storm of 

 January 26, 1SS4. 



THE THEORY OF SUNSPOTS 1 



'"P HE literature of heliograph)', by no means inconsider- 

 -*■ able in extent, has received an addition by the 

 publication of the work before us which, if it makes no 

 attempt to enlarge our knowledge of solar phenomena 

 from personal observation, is deserving of notice as a 

 specimen of one of the modes in which those phenomena 

 are attempted to be explained. 



The subject is confessedly full of difficulty as well as 

 interest. Nothing can be more natural than the wish 

 to obtain some knowledge of the constitution of that 

 splendid orb that is the dispenser of life and enjoyment 

 to unnumbered millions of organised beings, and that 

 exhibits on its surface such a strange development of 

 forces commensurate in intensity with its amazing mag- 

 nitude. But these tempting inquiries are beset with diffi- 

 culties scarcely to be appreciated in the absence of actual 

 experience. When we bear in mind the amount of light 

 and heat that has to be encountered, with all its conse- 

 quences in optical, mechanical, and atmospheric impedi- 

 ments, we may rather wonder that man should have been 

 permitted to accomplish so much, than that he should 

 have failed in effecting more. The serviceable working 

 of the telescope soon comes to an end : and what it is 

 able to exhibit it is not able to render intelligible. In 

 strong contrast with the exploration of the selenographer, 

 who feels no doubt as- to the general character of his 

 object, whatever perplexities may arise out of the study 

 of its details, the observer of the solar disk knows abso- 

 lutely nothing as to what he is looking upon. He finds a 

 blazing surface of by no means uniform texture, unlike 

 anything else in the whole compass of his experience. 

 He encounters strange-looking specks that disfigure, if we 

 might venture to use such a word without presumption, 

 the purity and perfection of that brilliant orb. In those 

 dark patches, and their attendant fringe-like borders, 

 what is it that meets the eye? Cavity? or cloud? or 

 eruption ? or cyclone ? or scoria ? Have astronomers 

 succeeded in explaining them ? Shall we listen to Wilson, 

 or Herschel, or Kirchhoff, or Nasmyth, or Secchi, or Faye, 

 or Zollner, or Langley ? More or less, they all disagree. 

 Or shall we be venturous enough to attempt an indepen- 

 dent solution of the mystery ? Little encouragement could 

 be found in such a course. After such protracted discus- 

 sion we could hardly bring to our telescope an unbiased 

 eye or an impartial judgment. What we are looking for, 

 we should be likely to find. We shall be surrounded with 

 phenomena that lend themselves with perplexing facility 

 to very dissimilar and even opposite interpretations : and, 

 .where one observer is confident as to a clear vacancy 



1 " Die Theorie den S^nn^nflec'cen. '* Nach den neuesten wissenschaft- 

 lichen Forschungen dirjssti'.I: m J. E. Broszus. iBerlin, 18 | ) 



leading down to unimaginable depths, another fills the 

 same dark area with heavy clouds or floating dross. There 

 may be, and for our own part we believe there are, as in 

 the formerly contested theories of light, details of less 

 equivocal character adequate to guide if not absolutely 

 to establish our judgment ; but the ambiguity of the 

 general aspect is sufficiently shown by the support which 

 such conflicting theories have claimed from it, each in its 

 turn. 



Perhaps we are disappointed in our telescope. It will 

 be to no purpose to enlarge our aperture or deepen our 

 eyepieces : we are still confronted by an insoluble mys- 

 tery. We adopt a fresh mode of investigation, the means 

 of which have been but recently placed in our hands ; 

 and we bid the spectroscope exert its analysing power and 

 report to us what is there. And now, under the guidance 

 of Lockyer and Janssen and Huggins, we shall be carried 

 a long way in advance, further than the boldest imagina- 

 tion would have dared to anticipate but a few years back ; 

 and we find set before us, as in some strange vision, the 

 unmistakable presence of familiar elements, ninety-three 

 millions of miles away. Yet even this triumph of human 

 ingenuity finds there a boundary that it cannot overpass. 

 The evidence, to a great extent conclusive, is sometimes 

 equivocal, sometimes perplexing : affected probably by 

 influences the force and direction of which we can little 

 estimate. The well-known features often wear a strange 

 aspect, and are associated with incomprehensible sur- 

 roundings. We have succeeded in interrogating the 

 sun : he has answered us, and his answer will surely be 

 reliable : — 



" Solem quis dicere falsum 

 Audeat ? " 

 That is, if we can but comprehend it ; but unfortunately 

 the message is not free from obscurity ; some of it is in 

 an unknown speech, and " Helium " and " No. 1474 " and 

 others of their companions are not only beyond our inter- 

 pretation, but are likely so to remain. Very wide is the 

 field thus opened for speculation, and very different may 

 be the deductions from the same, or apparently the same, 

 premises, with little possibility of demonstrating that any 

 one combines all the elements of truth. Not one of the 

 current theories has wanted defenders of intelligence and 

 skill ; if no one of them clears up all difficulties, no one 

 fails in showing that there is much to be said in its favour ; 

 and therefore, as long as no patent absurdity interposes an 

 insuperable bar, we may well exercise toleration to those 

 who do not see through our eyes, or who question to some 

 extent our conclusions. The best result is perhaps not 

 very far in advance of probability, and every claimant has 

 some right to be heard. 



Remarks somewhat of this nature may be suggested by 

 the treatise before us, which may be looked upon as an 

 attempt to stem the prevailing current of opinion as to 

 the cause of solar phenomena by showing that they may 

 receive a complete explanation from Zollner's theory of 

 floating scoriae, as expanded and developed by the author. 

 The principal results which he has deduced from an 

 extended collation, as it would appear, of the previous 

 observations of others, may be expressed in the following 

 way : — 



The sun is to be looked upon as an intensely heated 

 and very gradually cooling ball of monatomic gas, the 

 visible surface of which, or photosphere, is, as Kirchhoff 

 also maintained, composed of iron, with a small admix- 

 ture of other metals, in a state of glowing fusion, and 

 permeated in every direction by an abundance of incan- 

 descent hydrogen, this gas being poured forth abundantly 

 from the exterior of the monatomic nucleus, where the 

 central temperature is sufficiently reduced through de- 

 creasing density to admit of the first steps of elemental 

 association. The presence and diffusion of this hydrogen 

 maintains the fused condition of the iron shell, and pre- 

 vents it from cooling enough to exhibit in every part the 



