the complete neutralization of the two opposing forces, and leave
a small residual force acting towards the west and retarding the
rotation. Kant's conclusion was established, but by an action
different from that which he supposed.

The theory of Wright and Kant, which was still further developed
by Herschel, was that our stellar system has somewhat the form of
a flattened cylinder, or perhaps that which the earth would assume
if, in consequence of more rapid rotation, the bulging out at its
equator and the flattening at its poles were carried to an extreme
limit. This form has been correctly though satirically compared to
that of a grindstone. It rests to a certain extent, but not
entirely, on the idea that the stars are scattered through space
with equal thickness in every direction, and that the appearance
of the Milky Way is due to the fact that we, situated in the
centre of this flattened system, see more stars in the direction
of the circumference of the system than in that of its poles. The
argument on which the view in question rests may be made clear in
the following way.

Let us chose for our observations 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