160 G. H. KNIBBS. 



(29) Cauchy, 1839} — In 1839 Cauchy cursorily remarked in 

 connection with a brief discussion on the effect of motion on the 

 behaviour of luminous rays, that " if our sun move in space it 

 translates with it the whole planetary system"; and he points out 

 that on the supposition that the system to some extent carries 

 the ether with it, there is nothing extraordinary in the fact that 

 the refractions of luminous rays from stars in opposite points of 

 the heavens, viz., the points from which and to which we are 

 moving, are equal. This is probably one of the earliest recognitions 

 that the solar motion in space may perhaps produce optical effects 

 of an important character : a question however which has recently 

 been exhaustively discussed. See for example ''Aether and 

 Matter," by Larmor, Cambridge University Press, 1 900. 



(30) Gruithuisen, 1840? — In 1840 Gruithuisen, in a memoir in 

 the Astronomisches Jahrbuch for that year, pointed out that 

 meteors afford evidence of the path of the sun in space, 



(31) Lundahl, 184-0. — The Abo catalogue, by Argelander, did 

 not contain the whole of Bradley's stars given in the Fundamenta 

 Astronomic On comparing the latter work with Pond's cata- 

 logue of 1,112 stars reduced at the beginning of 1830, Lundahl 

 found as many as 147 stars with P.Ms, not less than 0-"09 annually, 

 which had not been included in Argelander's investigation. The 

 reduction of these gave the result 



R.A. = 252-°4, D. = +14-°4 



for the epoch 1792-5. Combining this result with those previously 



obtained by Argelander, and having regard to the weight of each,. 



gave for 1800 



R.A. = 257-°9, D.= +28-°8 



This investigation was published by Argelander in the Astrono- 



mische Nachrichten. 3 



1 Note sur l'egalite des refractions de deux rayons lu milieux qui emanent 

 de deux etoiles situees dans deux portions opposees de Pecliptique. — 

 Comptes rendus, vin., 1839, pp. 327-329. 



2 Die Sternschnuppen zei£en, wohin die Sonne den Weg im Weltraunx 

 ninamt. — Astr. Jahrb. 1840, 1 (Gruithuisen). 



3 Astr. Nach., No. 398, pp. 209 - 216. 



