ons that hour of the night at which the
Milky Way skirts our horizon. This is nearly the case in the evenings
of May and June, though the coincidence with the horizon can never be
exact except to observers stationed near the tropics. Using the figure
of the grindstone, we at its centre will then have its circumference
around our horizon, while the axis will be nearly vertical. The points
in which the latter intersects the celestial sphere are called the
galactic poles. There will be two of these poles, the one at the hour
in question near the zenith, the other in our nadir, and therefore
invisible to us, though seen by our antipodes. Our horizon corresponds,
as it were, to the central circle of the Milky Way, which now surrounds
us on all sides in a horizontal direction, while the galactic poles are
90 degrees distant from every part of it, as every point of the horizon
is 90 degrees from the zenith.

Let us next count the number of stars visible in a powerful telescope
in the region of the heavens around the galactic pole, now our zenith,
and find the average number per square degree. This will be the
richness of the region in stars. Then we take regions nearer the
horizontal Milky Way--say that contained between 10 degrees and 20
degrees from the zenith--and, by a similar count, find its richness in
stars. We do the same for other regions, nearer and nearer to the
horizon, till we reach the galaxy itself. The result of all the counts
will be that the richness of the sky in stars is least around the
galactic pole, and increases in every direction towards the Milky Way.

Without such counts of the stars we might imagine our stellar system to
be a globular collection of stars around which the object in question
passed as a girdle; and we might take a globe with a chain passing
around it as representative of the possible figure of the stellar
system. But the actual increase in star-thickness which we have pointed
out shows us that this view is incorrect. The nature and validity of
the conclusions to be drawn can be best appreciated by a statement of
some features of this tendency of the stars to crowd towards the
galactic circle.

Most remarkable is the fact that the tendency is seen even among the
brighter stars. Without either telescope or technical knowledge, the
careful observer of the stars will notice that the most brilliant
constellations show this tendency. The glorious Orion, Canis Major
containing the brighte