170 G. H. KNIBBS. 



R.A. required a correction in the form of x cos R. A. +y sin R. A. 

 the apparent drift would be at once accounted for. 



(58) Eeddie, 186 Jf. — The Astronomical Register of 1864 con- 

 tained an article by Reddie, expressing disbelief as to the motion 

 of the solar system in space. The paper provoked some anonymous 

 discussion in the pages of that journal, 1 but neither the paper nor 

 discussions contribute anything of permanent interest. 



(59) Babinet, 186 Jf. — Babinet, in an article in Cosmos in 1864, 

 discussed the possibility of the solar motion being that of one 

 component of a double star. 2 



(60) Stone, 1867. — In 1867 Stone considered the question of 

 the probability of the existence of solar motion, from the number 

 of cases of mere agreement or disagreement of the signs of the 

 proper motion and parallactic displacement. 3 His conclusion 

 was that the preponderance over the number required by mere 

 proper motion was sufficient evidence of the reality of the displace- 

 ment, but that on the whole, the parallactic displacement due to 

 the motion of our system through space was much smaller than 

 the independent proper motion of the stars. 



(61) Roek, 1868. — In reply to a query of Delaunay's as to 

 whether there was evidence of solar motion in the inclinations, 

 with the plane of the earth's orbit about the sun, of the planes of 

 the non-periodic comets, and also in their excentricities, Hoek 

 stated in 1868 that, subject to some uncertainty, the proper motion 

 of the sun would from such evidence appear to be insignificant as 

 compared with the mean initial motion of the comets, and from a 

 study of the excentricities it might be deduced, that the annual 

 path of the sun is probably inferior to three-tenths of the mean 

 radius of the earth's orbit. 4 It is fully recognised that such 

 deductions are essentially precarious. If the motions of non- 



1 Astron. Register, Vol. n., pp. 37-39, 59-61, 82-84, 87-88, 164-165, 

 1864. 



2 Cosmos, t. xxv., p. 429, 1864. 



3 Motion of the Solar System in Space. — Month. Not., Roy. Astr. Soc, 

 Vol. xxvii., pp. 238-239, 1867. 



* Comptes rendus, t. lxvi., pp. 1200-1207, 1868. 



