on Magnetic Attraction , 
297 
“ Inclined either way caus- 
ed very little alteration ” 
“ Inclined 60° E. made east 
face nearly all south, and west 
face nearly all north.” 
“ Compass placed at bottom of south face, had its south end 
attracted, but by inclining the ring 25° or 30° N., had its 
north end attracted, and at 
bottom of north face attract- 
t \ ed south, with the ring at all 
1 southerly inclinations. In shift- 
ing from NW. and SE. to W. 
and E., note the west face of 
s 
the ling becomes south.” 
In order to point out the results which should here be ob- 
tained, according to our hypothesis, I conceive a sphere to be 
described about the centre of the needle (as in Fig. p. 293.), and 
this sphere to be cut by a small circle, whose diameter is equal 
to that about the centre of the ring of iron, which the compass 
in the experiments described : then if the centre of the ring be 
carried in the circumference of this circle, the planes of the ring 
and circle coinciding, the ring and compass will have the rela- 
tive positions in the experiments. We must further observe, 
that the dip of the north end of the needle, where these obser- 
vations were made, was about 65°, so that the magnetic equator 
of the needle would be inclined to the horizon at an angle of 
about 25°, rising from the north. In the first experiment, the 
small circle cuts the magnetic meridian and the horizon, at right 
angles, and is unequally divided by the magnetic equator. Let 
us suppose that the ring is to the south of the compass, as in 
the left hand figure. Then, when the centre of the ring is in the 
magnetic equator, the situation in which, according to our hy- 
pothesis, it will not affect the horizontal needle, the compass is 
opposite to a point above the centre of the ring. When the 
