144 PROCEEDINGS OF THE AMERICAN ACADEMY 



surae most astronomers would agree in considering Calandrelli's argu- 

 ment as irrelevant. 



In No. 28 of Pi'ofessor Briinnow's valuable "Astronomical Notices" 

 I have shown that, in spite of the misapprehensions to which I have 

 just alluded, the observed motion of Sirius in declination is in fact 

 represented by a formula depending on the previous investigation of 

 Peters, but with four new unknown quantities inserted. The addition 

 of these four quantities, which I have determined by least squares, en- 

 ables us to state with a certain degree of accuracy the angle of position 

 of the centre of gravity with respect to the visible mass, and thus the 

 angle of position of the supposed invisible companion. 



Closely following the actual publication * of this memoir, came the 

 discovery t of the companion by Mr. Clark. The question at once 

 arose, whether this were the disturbing body ; the evidence bearing 

 upon this appeared very noteworthy. In the first place, the angle of 

 position agreed (within the uncertainty of observation) with that com- 

 puted for the disturbing body, assuming my investigation | as the basis. 

 The following table shows the relation for 18G2 between computation 

 and observation. To my own computation I have added the similar 

 one of Auwers, published afterwards. § 



The difference between Dr. Auwers's theoretical investigation and 

 my own is perhaps not larger than the uncertainty of all the series of 

 observations on Sirius would explain ; as I have before stated, the 



* The number bears date, Dec. 20, 1861 ; my own communication, Sept. 20th. 



t Jan. 31, 1862. First announced by Professor Bond, in No. 13.53 of the Astro- 

 nomische Nachrichtcn. 



|; This fiict was stated by Professor Bond (American Journal of Science for 

 March, 1862, p. 287). 



§ Astronomische Nachrichten, No. 1371. It is proper for me here to express 

 my sense of the courtesy with which Dr. Auwers admitted my priority in the matter 



II Astronomische Nachrichten, No. 1374. 



11 Ibid., No. 13,55. 



** Ibid., No. 1360. 



tt American Journal of Science, May, 1863, p. 407. 



