Local System and Draper Extension 69
classes the respective plots present the distribution through-
out a definite, relatively small, interval of distance from
the observer. What this distance is varies from class to
Figure 7. Class F stars of magnitudes 10.1 to 11.0 in the Taurus
region of the Henry Draper Extension.
class, depending of course on the absolute luminosities of
the different types of stars. For Classes G, K, and M, in
which giants and dwarfs are mixed, two intervals of dis-
tance are represented.