174 L. Trouveht— Veiled Solar Spots. 



tliat very few spots have been observed outside of the zones 

 lying 40° on either side of the equator. I know of but two 

 instances on record in which spots have been observed beyond 

 this limit. La Hire observed a spot 70° from the equator, and 

 more recently, in the month of June, 1846, Dr. C. H. F. Peters 

 observed at Naples a spot 60° from the equator. 



It is further to be remarked that accordinor to the conclusions 

 of the English observers, the solar spots attain higher latitudes 

 during the years of the maximum number of spots, and recede 

 more and more towards the equator as the minimun is ap- 

 proaching; and it is to be uoted that the present ^ear is pre- 

 cisely, or at least very nearly, a minimum year. It is doubtless 

 owing to the unusual thinness of the chromosphere during 

 this period that spots have been observed in so high latitudes 

 this year. It is true that the spots were small, but, neverthe- 

 less, they were genuine spots, with all the characteristics of 

 larger spots. 



It is difficult for one who has seen the phenomena which I 

 have described, to come to any other conclusion than this: that 

 the veiled spots are breaks or 'true openings in the photosphere, 

 seen through the imperfectly transparent gases composing the 

 chromosphere, openings themselves partly or wholly filled by 

 the vapors ejected by the forces from the interior of the photo- 

 sphere. If this hypothesis should prove to be the expression 

 of a fact, then we should expect to find that the photosphere is 

 perforated by thousands of crevasses either partly or entirely 

 filled with the vapors and gases from the interior, which cannot 

 be ejected outside for want of sufficient energy, save for a com- 

 paratively very small number situated in the equatorial zones, 

 where this energy appears maximum, and is able to repel and 

 dissolve the gases from the interior. 



Before the observations of this year, I had arrived at pre- 

 cisely the same conclusions in regard to the opening of the pho- 

 tosphere in all latitudes, and to the existence of invisible spots 

 concealed by the chromosphere. These conclusions were derived 

 from my observations with the spectroscope, made at Harvard 

 College observatory during a period of thirty-five months. A 

 discussion of these observations is reserved for a future corn- 

 Though one can hardly form a settled opinion with regard to 

 the cause of the general depression of the chromosphere, on 

 account of the imperfect data, it seems natural, however, to sup- 

 pose that the phenomenon is connected in some way with the 

 minimum period of sun spots. Judging by the great number 

 of veiled spots observed, and by the myriads of pores seen 

 between the granulations, it would seem that both the chromo- 

 sphere and photosphere have been much thinner than usual 

 during the present year. 



