Revised spectral classes for B8-A~ stars north of +800 declination confirm essentially the variation of interstellar absorption with distance found by Stebbins, Huffer, and Whitford for these stars. The total visual absorption, which is inappreciable for distances less than 200 parsecs, increases to 0.3 mag. at 400 parsecs
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Keenan et al. (1941) studied this question.