The name is absent

16          Sidereal Explorations

It is clear from Figures 11 and 12, with the addition of
Figure 6, that the number of Class A stars increases with
decreasing brightness at different rates in different parts of
the sky. In heavily nebulous regions the increase is slow;
in transparent regions where the remote A stars are not lost
by intervening nebulosity the increase is rapid. I have
selected five different areas in the Taurus region for which
the frequency curves are tabulated in Table III and plotted

Table III

Number of Class A Stars Per Square Degree
in Taurus

in Figure 13. The areas are arranged in order of increasing
richness in stars between magnitudes ten and eleven; Area 1
is the most heavily obscured, Area 5 is nearly if not quite
free of obscuration. Although there is little difference in
the number of Class A stars per square degree brighter than
the eighth magnitude, at the tenth magnitude Area 5 is thir-
teen times as rich as Area 1. Obviously the form of the
frequency curve of apparent magnitude depends on the
area observed.

The average giant star, with a luminosity a hundred times
that of the Sun, is about five thousand light years distant

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