v.] The Entrance of the Depths. i 71
other, we are compelled to recognize what is
called the Invariable Plane of the Planetary
System, the plane, that is to say, about which,
as La Place demonstrates, certain highly im-
portant relations between the masses and the
motions of the planets are always fulfilled.
Now this plane has never a greater inclination
than about 3° 6' to the apparent ecliptic, that
is, the plane of the orbit of the earth. But that
arc (3° 6') measures within a few minutes the
distance of the pole from the pole-star when
in conjunction, so to speak, with the Grand
Pyramid. When therefore the pole-star shines
down the entrance passage, its position in
regard to the pole (due allowance being made
for corrections), defines the limiting position
°f the invariable plane to the plane of the
orbit.
Similarly in regard to the inconceivably
slow variation * in the inclination of the axis
* See the table and memoir published by the Smith-
sonian Institute of Washington.
other, we are compelled to recognize what is
called the Invariable Plane of the Planetary
System, the plane, that is to say, about which,
as La Place demonstrates, certain highly im-
portant relations between the masses and the
motions of the planets are always fulfilled.
Now this plane has never a greater inclination
than about 3° 6' to the apparent ecliptic, that
is, the plane of the orbit of the earth. But that
arc (3° 6') measures within a few minutes the
distance of the pole from the pole-star when
in conjunction, so to speak, with the Grand
Pyramid. When therefore the pole-star shines
down the entrance passage, its position in
regard to the pole (due allowance being made
for corrections), defines the limiting position
°f the invariable plane to the plane of the
orbit.
Similarly in regard to the inconceivably
slow variation * in the inclination of the axis
* See the table and memoir published by the Smith-
sonian Institute of Washington.