222 ASTRONOMY: F. H. SEARES 
shown in the seventh column of the table is little affected by differ- 
ences in the limiting brightness. This divergence indicates that, as 
compared with both Kapteyn and Mount Wilson, their results are not 
homogeneous; and noting, further, that the numerous and careful 
guages of the Herschels which extend to the 14th magnitude give a galac- 
tic condensation agreeing closely with Kapteyn (Herschel 12.9, Kapteyn 
11, Chapman and Melotte 3.9), one gains the impression that, through 
some unknown cause, their counts in the richer fields fail to include 
many of the fainter stars. 
^ Wright, T., Theory of the Universe, London, 1750. 
2 Kapteyn, J. C, Puh. Astr. Lab. at Groningen, Groningen, No. 18, 1908, (1-54). This 
memoir includes bibliographical references to earher investigations. 
3 Chapman, B. A. and Melotte, P. J., Mem. R. Astr. Soc, London, 60, 1914 (145-173). 
* Parkhurst, J. A., Researches in Stellar Photometry, Washington, Carnegie Inst., 
Pub., No. 33, 1906, (1-192). Similar results for the fields of several variable stars have ap- 
peared from time to time in the Astrophysical Journal. 
5 Scares, F. H., These Proceedings, 3, 1917, (188-191). 
A CORRECTION 
Professor Alexander McAdie has kindly drawn my attention to an error in 
dates occurring in my paper, Inferences Concerning Auroras, published in the 
Proceedings for January, 1917, pages 1-7. In reference to the "Aurora of 
April, 1883", he has convinced me from his data that the particular event 
occurred on November 17, 1882. My mistake was due to faulty references, 
and in no way affects the general argument. 
ELIHU THOMSON. 
