172 L. Trouvelot— Veiled Solar Spots. 



At 2*» 0™ P. M., on the same day, several small black spots 

 had opened through the chromosphere upon the group of veiled 

 spots observed in the morning. At &" 0™ on the followmg 

 morning, the group of small black spots was considerably 

 increased, having quite a large spot on the preceding side, 

 followed by twelve or fifteen smaller ones. On June 24, this 

 group had attained to its maximum size. It was then very 

 large and complicated. In fact, it was the largest group of sun 

 spots observed thus far during the present year. 



On August 8, I noticed a group of veiled spots a little south 

 of the sun's center. The following morning at 7^ 0'", there 

 was at the same place a small group of half a dozen black spots 

 disposed in a crescent shape. At 2i» 0'" P. M., the black spots 

 had vanished, but the veiled spots still remained, having 

 retained the characteiistic crescent form of the black spots and 

 many other details observed in the morning ; and, as a proof 

 that the chromosphere covered this spot, the granulations could 

 he plainly seen upon the whole, indicating clearly that this spot was 

 seen through the veil of the chromospheric gases. 



On August 24, the same phenomenon took place. Just fol- 

 lowing the principal spot of the only group then to be seen on 

 the surface of the sun, there was a fine group of veiled spots. 

 The following day some black spots had made their appearance 

 upon them. On August 27, the black spots had vanished, but 

 in their place the veiled spots seen at first still remained, and 

 they continued to be seen there for several days. 



To all appearances, the black spots which I had seen dis- 

 appear under the chromospheric gases, and which continued as 

 veiled spots, were exactly alike and undistinguishable from the 

 many other veiled spots scattered all over the sun ; and, had I 

 not seen the 

 I could not 1 



So far, I have only spoken of veiled spots observed in the 

 zones where the ordinary sun spots usually make their appear- 

 ance ; but, as I have said, the veiled spots are scattered all over 

 the surface of the sun. 



During this period, I had many occasions to observe very 

 remarkable and characteristic veiled spots in very high helio- 

 graphic latitudes north and south. On July 15, within a few 

 degrees of the north pole of the sun, I observed a remarkable 

 veiled spot, unusually large and dark. Upon it were several 

 bright slender facula3 projected in crest shape to very high 

 altitudes. These faculse appeared to be precisely like those 

 observed in lower latitudes near ordinary sun spots." Upon this 

 veiled spot could unmistakably be seen" a small black spot, not 

 a pore ; a real opening of both chromosphere and photosphere. 



