460 Proceedings of Philosophical Societies. [June, 



armed with the most powerful means, we anticipate the most 

 successful results from his laborious exertions. Unconscious 

 of what was going forward in this country, he had opened for 

 himsetf a vast field of inquiry, which he has pursued with 

 the most splendid success ; and which places his name amongst 

 the most celebrated of modern astronomers. The Paper which 

 has been read to us, this evening, shows that his ardor is 

 unabated : since he there announces the important fact of the 

 observation of 1000 double stars of the first four classes (most 

 of which are entirely new), and amongst which are 300 of the 

 •first class. To a mind, formed like his for the pursuit of 

 science, little need be said to animate him to a continuance of 

 his labors : but, it may be pleasing to him to know that we are 

 alive to the progress of his discoveries : and I am sure that you 

 will convey to him, in much better terms than I can do, the ex- 

 pressions of our esteem and admiration for his services in the 

 cause of science ; — services which assure us that the name of 

 iStruve will be imperishable in the annals of astronomy." 



At this meeting was also read, " A Comparison of Ob- 

 servations made on Double Stars." Communicated in a 

 letter to J. F. W. Herschel, Esq. Foreign Secretary to this So- 

 ciety, by Professor Struve, of Dorpat. Addressing himself to 

 Mr. Herschel, M. Struve, says, " You may easily imagine with 

 what interest I have perused the work on double stars, by your- 

 self and Mr. South, and with what pleasure I found that, inde- 

 pendently of one another, we have arrived at the same results 

 and deductions. Although my instruments were formerly in- 

 ferior to yours, with respect to measurements (as I could only 

 observe differences of AR on the meiidian, and angles of po- 

 sition with a 5-feet telescope of Troughton), they may be con- 

 sidered in an optical point of view equal to yours ; viz. the 

 5-feet telescope of Troughton's to yours attached to the 5-feet 

 equatorial; and the 8-feet one of DoUond to yours attached 

 to the 7-feet equatorial ; and after receiving the repeating mi- 

 crometer of Fraunhoi'er, which I fixed to Troughton's telescope, 

 every desideratum in this instrument was fulfilled." 



M. Struve, however, found himself involved in some prac- 

 tical difficulties, until the arrival of Fraunhofer's large re- 

 fractor, an instrument whicli, with respect to double stars, left 

 him nothing further to wish ; and he determined on a new ex- 

 amination of all the double stars observed before (whether by 

 Sir W. Herschel, Messrs. Herschel and South, or himself,) as 

 well as on a minute inquiry of the heavens from the north 

 pole to — 15° of declination, with respect to these objects. 

 He has now accomplished one-third of the labour, and has 

 found 1000 double stars of the first 4 classes ; among which 800 



