218 
ASTRONOMY: F. H. SEARES 
conditions. Seeliger's results, based mainly on the great Bonner Durch- 
musterung catalogues of nearly half a million stars, though affording 
results for graduated intervals of brightness, do not go below the 10th 
magnitude. Celoria's counts include fainter objects, but, like those of 
the Herschels, are only totals for a certain range of magnitude. 
To revise these results and extend them to the stars within reach of 
modern telescopes, Kapteyn, in 190^8, discussed all the reliable data 
then available. His magnitudes for the fainter stars are on the visual 
scale of Parkhurst,^ and to the 15th magnitude depend on photometric 
standards. Beyond this his tables of distribution are extrapolated, 
but the changes with increasing magnitude are so regular that his values 
should be reliable to a somewhat fainter limit, provided the photometric 
standards are not in error. 
The latest study of stellar distribution, depending largely on the 
excellent photographs secured on the initiative of FrankKn-Adams, is 
also of special interest. Transferring the scale of the Harvard Polar 
Sequence to thirty of the Franklin-Adams regions by means of inter- 
comparison photographs, Chapman and Melotte derived values of 
the star-density for magnitudes 12 to 17. Other plates gave results 
for the brighter stars, which also are referred to the Harvard photo- 
graphic scale. 
A comparison with Kapteyn's results reveals two important facts: 
{a) Kapteyn's total of stars in the whole sky to specified limits of 
magnitude is systematically the larger. Approximately 50% greater 
from the 4th to the 10th magnitudes inclusive, it increases rapidly 
for fainter limits, and at the 17th magnitude is 7 times that of Chap- 
man and Melotte. 
{h) With increasing magnitude, the galactic condensation (ratio 
of star-density at galactic latitude 5° to that at 80°) increases: 
Limiting Magnitude 5 7 9 11 13 15 17 
Kapteyn 2.13 2.25 2.82 4.3 7.9 17.5 44.8 
Chapman and Melotte.. . 2.06 2.26 2.69 3.2 3.7 4.1 4.3 
To the 9th magnitude there is agreement, but beyond, Kapteyn's 
values are greatly in excess. 
The difference noted in {a) is, in part, to be expected, for in one case 
the magnitudes are visual, in the other, photographic. The number of 
stars to a specified visual limit is necessarily greater than that to the 
same limit on the photographic scale, the excess depending on their 
color. To the 10th magnitude the two results thus agree well enough; 
