6 | 6.11| + 5 | 8.2 | + 8.5 |G | 9.1 |
|23|Bradley 1584 | 1.06| - 5 | 6.1 | + 6.2 |G | 6.9 |
+--+-----------------------+------+--------+---------+---------+----+------+
| | | |sir./st.| | | | _m'_ |
| | Mean | 3".42| 9.1 | 6m.3 | +7m.3 |G6 | 7.5 |
+--+-----------------------+------+--------+---------+---------+----+------+

The mean absolute magnitude of the near stars is distributed in the
following way:--

_M_ 0 1 3 4 5 6 7 8 9 10 11 12 13
Number 1 2 1 2 1 2 1 4 4 1 1 1 1.

What is the absolute magnitude of the near stars that are not contained
in table? Evidently they must principally be faint stars. We may go
further and answer that _all stars with an absolute magnitude brighter
than 6m_ must be contained in this list. For if _M_ is equal to 6 or
brighter, _m_ must be brighter than 6m, if the star is nearer than one
siriometer. But we have assumed that all stars apparently brighter than
6m are known and are contained in the list. Hence also all stars
_absolutely_ brighter than 6m must be found in table 5. We conclude that
the number of stars having an absolute magnitude brighter than 6m
amounts to 8.

If, finally, the spectral type of the near stars is considered, we find
from the last column of the table that these stars are distributed in
the following way:--

Spectral type B A F G K M
Number 0 2 2 5 9 3.

For two of the stars the spectrum is for the present unknown.

We find that the number of stars increases with the spectral index. The
unknown stars in the siriometer sphere belong probably, in the main, to
the red types.

If we now seek to form a conception of the _total_ number in this sphere
we may proceed in different ways. EDDINGTON, in his "Stellar movements",
to which I refer the reader, has used the proper motions as a scale of
calculation, and has found that we may expect to find in all 32 stars in
this sphere, confining ourselves to stars apparently brighter than the
magnitude 9m.5. This makes 8 stars per cub. sir.

We may attack the problem in other ways. A very rough method which,
however, is not without importance, is the following. Let us suppose
that the Galaxy in the direction of the Milky Way has an extension of
1000 siriometers and in the direction of the poles of the Milky Way an
extension of 50 sir. We have later to retur