1889.] on the Solar Sur/ace during the Last Ten Years. 505 



seem to connect them more immediately than any other feature of the 

 solar surface with the vertical convection currents which form so 

 important a part of the sun's internal economy. 



One exceptional observation of the formation of veiled spofcs may 

 be of interest, as showing the strange phenomena we may occasionally 

 witness by a lengthened examination of the solar image. At lOh. 

 15m. one morning a group of spots was visible on the sun, and 

 presented no very special feature ; less than half an hour later the 

 leader of the group had apparently shot out a number of minute 

 bodies, and then five minutes sufficed for all these to be transformed 

 into veiled spots, which disappeared as rapidly as usual. 



Instances have not been wanting of other moving bodies seen 

 upon the solar surface, always rapid in their course, and sometimes 

 disappearing without crossing the limb. I refer, of course, only to 

 observations in which every precaution was taken to test the objective 

 nature of these bodies, as false images might so easily deceive a 

 tired retina, especially after exposure to a strong light. But there 

 would be little use in dwelling upon even well-established cases of 

 this nature, as they all probably find their explanation in the 

 passage of bodies between the sun and the observer, and promise 

 very little additional light for an inquiry iLto the nature of the 

 solar photosphere. 



Before concluding these few words on a series of solar obser- 

 vations of the last ten years, I may be expected by some to add one 

 more to the already long list of solar theories, or at least to pass in 

 rapid review the most plausible theories that up to the present time 

 have been advanced for reducing to harmony all the well-established 

 facts regarding the sun with which we are acquainted. But con- 

 sidering the scope of my discourse, which has dwelt mostly on the 

 work done at a single observatory, and, even so, has only treated in 

 detail one method of examining the solar photosphere, I should not be 

 warranted in advancing any theory of my own, or in judging of the 

 theories of others, without first considering the many important facts 

 connected with our subject which the spectroscope has taught us and 

 also extending my researches to the solar chromosphere and the corona. 

 It is only by diligently collating the facts laboriously accumulated by 

 telescope and siDcctroscope in every known region of the sun that we 

 may hope at last to build up a complete and satisfactory solar theory. 

 Much has already been achieved in this direction, and we are in 

 possession not only of reliable data, but also of important deductions 

 therefrom, which may serve as a solid foundation for some future 

 superstructure. 



I may have added, perhaps, some little towards the completion of the 

 edifice, if I have convinced you this evening, that by the persevering 

 and judicious use of the pencil we may yet hope to throw some light 

 on questions of solar physics, that might not|_so readily have been 

 secured by any other means. I S. J. p. ] 



