562 Royal Astronomical Society. 



The President (Sir J. F. W. Herschel, Bart.) then addressed the 

 Meeting on the subject of the award of the Medal, as follows:— 



Gentlemen, — The Report of the Council has placed hefore you 

 so ample a view of the state of the Society, of its labours during 

 the last year, of the accessions to its members, and of the many 

 and severe losses it has had to deplore, that little is left for me to 

 add, except my congratulations on its continued and increasing pros- 

 perity. It would be inexpressibly gratifying to me if I could per- 

 suade myself that my own exertions in its Chair had contributed, 

 even in a small degree, to that prosperity ; but, alas ! I have felt 

 only too sensibly how very feebly and inefficiently, especially du- 

 ring the last year, owing to a variety of causes, but chiefly to resi- 

 dence at a distance from London, I have been able to fill that most 

 honourable office. 



The immediate object of my now addressing you, gentlemen, is 

 to declare the award by your Council of the gold medal of this So- 

 ciety to our eminent associate, M. Bessel, for his researches on the 

 annual parallax of that remarkable double star 61 Cygni *, researches 

 which it is the opinion of your Council have gone so far to establish 

 the existence and to measure the quantity of a periodical fluctua- 

 tion, annual in its period and identical in its law with parallax, as 

 to leave no reasonable ground for doubt as to the reality of such 

 fluctuation, as something different from mere instrumental or ob- 

 servational error : an inequality, in short, which, if it be not parallax, 

 is so inseparably mixed up with that effect, as to leave us without 

 any criterion by which to distinguish them. Now, in such a case, 

 parallax stands to us in the nature of a vera causa, and the rules of 

 philosophizing will not justify us in referring the observed effect to 

 an unknown and, so far as we can see, an inconceivable cause, when 

 this is at hand, ready to account for the whole effect. 



I say, in the nature of a vera causa, since each particular star 

 must of necessity have some parallax. Every real, existing material 

 body, must enjoy that indefeasible attribute of body, viz. definite 

 place. Now place is defined by direction and distance from a fixed 

 point. Every body, therefore, which does exist, exists at a certain 

 definite distance from us and at no other, either more or less. The 

 distance of every individual body in the universe from us is, there- 

 fore, necessarily admitted to be finite. 



But though the distance of each particular star be not in strict- 

 ness infinite, it is yet a real and immense accession to our know- 

 ledge to have measured it in any one case. To accomplish this, has 

 been the object of every astronomer's highest aspirations ever since 

 sidereal astronomy acquired any degree of precision. But hitherto 

 it has been an object which, like the fleeting fires that dazzle and 

 mislead the benighted wanderer, has seemed to suffer the semblance 

 of an approach only to elude his seizure when apparently just within 

 his grasp, continually hovering just beyond the limits of his distinct 



[* See Phil. Mag., Third Series, vol. xiv. p. 226.— Ed.]. 



