dip in higher latitudes passes beyond the pole.
But in the third position of the terrella the needle is perpendicular; because the pole of the stone is placed at the top, and the needle tending straight toward the body reaches to the pole. The cross in the preceding figures always turns toward the boreal pole of the terrella, having been touched by the boreal pole of the terrella; the cusp of the needle, having been touched by the southern pole of the stone, turns to the south. Thus one may see on a terrella the level, oblique, and perpendicular positions of a magnetic needle.
CHAP. II.
Diagram of declinations of the magnetick needle, when
excited, in the various portions of the sphere, and horizons
of the earth, in which there is no variation
of the declination.
As
