693 



be seen at once, liow the difference in distance of tlie stars 

 wil! affect (lie results by this nielliod. This investigation gave 

 Apv^,,,.,, =r-|-0".43, iviiile the R.A. after applying our correction 

 gave A/>x,„,.= + 0". 7(5 + 0".33 = + 1".09. In these results loo, 

 catalogue-ei'rors probably play a considerable part. 



Finally we must draw attention to the terms which we found, 

 depending upon 2« and 3», amongst which there are some wiiich 

 may attain values which can certainly not be neglected. 



We have in R.A. the terms-. 



r 



+ 0.11 sm2rf— cos 2 a 



0.10 cos^ Ö cos 3« 



R,„ 



that is for stars of the magnitude 5™. 5: 



— 0".29 sin -Zii cos 2« + 0".26 cos-" d cos 3rt 

 and in Dee!., to confine ourselves to the terms in 2«, 



Z Z 



— 0.08 cos' (f sill 2<( — 0.20 cos' ö cos 2« 



rC„i Jxjii 



that is for stars 5'". 5 



— 0".r2 cos^ ifsin 2« — O"..S0 cos' (I cos 2«. 

 These terms will, when we do not take account of them in our 

 calculations, be added to the corres|)onding ones arising from periodic 

 catalogue-errors, and show all the more clearly, that no conclusions 

 can be easily drawn from limited areas of R.A., and that it is 

 advisable in investigations of this kind as far as possible to give 

 e(pial weights to the different R.A. -groups. 



Jn the second place ine investigate the influence of the assumed 

 lam of distances upon the determination of the paraUactic motion. 



We assume here that the A' and 3^-coraponents are deduced 

 from the R.A. only, that is, from the terms which depend respectively 

 upon slnu and cos a, and that for the determination of A' a value 

 of A// is introduced, which is deduced from other terms (/?; in a, n 



' X 



R,n 



we regard the distance as only dependent upon the magnitude, and 

 act in the same way with regard to the two other components, 

 and if we further apply a few simple transformations, as was 

 already partially done above, we get 



in (ƒ). If we then indicate by 



the value which is found when 



'A' 

 Y 



0.93- 



0.93 



A' 



Rm 



Y 



0.04 cos' Ó 



R,r. 

 X 



0.0't cos'' d h 0.20 cos- d 



R,n 



Y 



