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ASTRONOMY: F. H. SEARES 
deviations are very small — in most cases within the uncertainty which 
necessarily affects the discussion of- the data. To this extent, therefore, 
we may look upon them as supplying a very satisfactory confirmation 
of Kapteyn's results. This fact is further illustrated by the following 
series of values for the galactic condensation (ratio of number of stars 
at 5° to number at 80°). 
Limiting Magnitude .. 8.5 9.5 10.5 11.5 12.5 16.0 
Kapteyn 2.6 3.1 3.8 4.9 6.7 27 
Astrographic Zones 2.4 3.2 3.8 4.7 6.2 
Arequipa, Selected Areas ... .... .... .... 21 
Mt. Wilson, Selected Areas 21 
It is important to note that the use of Kapteyn's density table for the 
determination of the limiting magnitudes of the counts has not artificially 
forced an agreement with his values of the galactic concentration. The 
use of a limit thus derived for any zone in no wise affects the rate at 
which the density observed within that zone increases with decreasing 
latitude. The results are referred to Kapteyn's scale of magnitudes, but 
this influences only indirectly the value of the condensation for any 
specified limit. 
A comparison of the counts for the different zones with the meaii dis- 
tribution table whose derivation has been outlined reveals large devia- 
tions in individual cases. To what extent these represent local variations 
in stellar density cannot now be determined. Professor Turner has been 
led to believe^ that the Astrographic data give evidence of a spiral of 
obscuration encirchng the sky, in which the ratio of the number of faint 
stars to bright stars is abnormally low. But his discussion seems not to 
include the influence of the increase in galactic condensation with increas- 
ing magnitude, which appears so clearly in the numbers appended to 
the preceding paragraph. When this has been duly allowed for, the 
fluctuations in the ratio of faint stars to bright stars assume an accidental 
character; doubtless they correspond in part to actual variations in 
density, but differences in observing conditions must also have contrib- 
uted much in producing the irregularities. 
1 Scares, F. H., these Proceedinhs, 3, 1917, (217-222). 
2 Kapteyn, J. C, Groningen, Pub. Astr. Lab., No. 18, 1908, (1-54). 
3 Chapman, B. A., and Melotte, P. J., London, Mem. R. Astr. Sac, 60, 1914, (145-173). 
^ Published by the Astronomical Laboratory at Groningen, 1911, (1-34). 
^ Turner, H. H., Numerous articles in London, Mon. Not. R. Astr. Soc, 72, 75, 76, 77, 
1909-1916. 
^ Kapteyn, J. C, First and Second Reports, Groningen, 1911, (1-34), p. 15. 
7 Turner, H. H., London, Mofi. Not. R. Astr. Soc, 76, 1915, (149-157), p. 152. 
