521 



of the American Astronomical Society. Popular Astro7iom>/ 25, 

 108—110, 1917. 



9. W. G. Thackeray. Notes on some Proper Motions derived 

 from a Comparison of Carrington's Catalogue with the Greenwich 

 Places for 1900. Monthly Xotices 67, 146—148, 1906. 



Boss' catalogue was only used for stars brighter than 5»'.8. 



AuwERs' catalogue was only used to determine A^,,,,,,. for the 



whole sky. 



The proper motions that have been derived from the Cape plates 

 in Publ. Groningen N". 25, are not very accurate. The plates had 

 not been originally destined for deriving proper motions from them, 

 and they had been measured absolutely. We have, therefore, in 

 determining the mean values attached but very little weight to them. 

 No corrections have been applied in order to reduce our results 

 for the different catalogues to the same scale of magnitudes or to 

 one fundamental system or in order to correct the proper nu)tions 

 for errors of observation. These corrections may in our opinion be 

 neglected, considei-ing the comparative inaccuracy of the numbers. 

 Moreover, we have always expressed the numbers xV,,,.,,. for every 

 magnitude in percentages of the numbers A\a and these percentages 

 appeared to vary only little with the magnitudes. 



Onr countings in determining .V,„,. tbi- the whole sky include 

 38818 proper motions, while moreover in the live zones resp. 8273, 

 10857, 6981, 3144 and 1488 stars were counted. 



Now we are able to determine the numbers of stars of determined 

 magnitude and proper motion. The results we found for the whole 

 sky, are mentioned in table 1. 



In our further research we ditl not use the numbers of stars 

 with fx>50". It is very difticult to determine these with sufficient 

 accuracy from the data of known proper motions, so scanty as yet. 

 It will appear that in consequence of this limitation we could not 

 extend the luminosity curve found by us to the faintest stars. 



The numbers zV,„,l now being known for the different zones, we 

 may also examine' how the stars with determined proper motions 

 are distributed over the sky with reference to the Milky Way. In 

 order to do so we have calculated the numbers of stars with P.M. 

 resp. > 10", 5", 3" and 0" for every magnitude per 100 square degrees. 

 It appeared that the numbers of stars with ji > 5" do not evince 

 any galactic condensation, except perhaj)S for stars, fainter than 

 9"'.0. The numbers with fi > 3" very clearly show a condensation 

 for all magnitudes in the direction of the Milky Way, although to 

 a less high degree than the numbers of stars with ft > 0". 



