44 



THE POPULAR SCIENCE MONTHLY. 



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A Typical Sun-spot. 



ment of fact, or every expression of opinion, is based upon a hundred 

 single instances like the one which is chosen, or upon a hundred con- 

 curring judgments. It is not that you are overborne by weight but 

 convinced by character. This most important paper came at exactly 

 the right time. It first summarizes the works of other recent observ- 

 ers, which, though important, had left the subject in an entirely un- 

 satisfying condition, and then proceeds straight to the subject in 

 hand. 



The minute details, both of the general solar surface and of the 

 extraordinarily complex spots, are one by one satisfactorily and lucidly 

 described, with indications of the physical conditions to which they 

 are due ; and, finally, the general bearings of all this on the received 

 solar theories are briefly set forth. We may fairly say that this paper 

 is fundamental. It treats of a subject of which little had been accu- 

 rately known, and it leaves this subject in a satisfactory and settled 



