XXVIIL] VEILED SPOTS. 409 



when examined by the spectroscope is found to be a true spot. 

 These fine mottlings sometimes take certain directions, in conse- 

 quence of the existence of powerful currents. Here and there we 

 get cyclonic swirls, and here and there there is an appearance 

 of smudginess, apparently produced by tremendous overhead 

 currents, so to speak, that is, currents between us and that part 

 of the sun on which they appear. 



(2) Veiled spots. In addition to these pores M. Trouvelot 

 discovered about ten years ago a kind of spot which he calls 

 veiled spots; in those regions where they occur his opinion is 

 that the photosphere is driven down to a certain extent, but not 

 driven down sufficiently to give us the dark appearance which 

 we get in the spots of the ordinary kind. 



Some spots again take the appearance of enlarged pores, that 

 is they have no penumbra, and others again appear as intensified 

 veiled spots, that is to say they have no umbra, but the 

 penumbral shade is very well developed. 



Independently, then, of the phenomena of the large obvious 

 so-called "spots/* ample evidence has been secured by minute 

 observation to show that the whole photosphere is traversed by 

 down-rushes, some of them possibly of almost infinitesimal 

 dimensions, and others varying in importance till the most 

 tremendous manifestations of the action are developed. 



When we come to examine these spots carefully, we find that 

 there are apparently in the main (I wish to speak as guardedly 

 as I can) two different kinds. 



(3) Quiet spots. Some spots seem to be pretty regular, and to 

 undergo no very violent commotion. I mean that the penumbra 

 and the umbra are not so tremendously contorted and mixed up 

 as sometimes happens ; and again, the ridge of facula round the 

 spot is not so honeycombed by convection currents and lateral 

 currents and their results. 



(4) Disturbed spots. On the other hand, as representing the 

 other class where we get violent action, there seems to be no 



