* Sl e Vacan * space left in the map near its centra 
ts ‘bo be filled by the observer’s imagining how the i n ’ 
Her meridians would appear if exhibited under the 
general circumstances! describe,including refraction 
I conclude that it is at the real verge, where the* 
excessive and permanent variation, prevailing hi°h 
north, begins, and that such variation is owing to the 
curvature of the meridians, and not to any deviation 
of the needle; and that the needle will neariy corres¬ 
pond with the clock, as far within the sphere as it 
w-ill continue to traverse and settle towards any defi¬ 
nite point. In other words, the clock will disagree 
with the sun as much as the needle does. It appears 
probable, that beyond and within the verge, the in¬ 
tensity ot the magnetic force gradually decreases as 
one progresses towards the inner equator; and, that a 
great sterility of soil, and a subsoil frequently frozen 
all summer, with an inclement climate, commences 
o ~ » 1'. - < ■» -- . ... 7 
yi ur a nme oeyono the extremity £jf the real verge— 
These circumstances cannot, however,continue much 
beyond the apparent ver^e„ I also conclude thrt but 
few ot the migrating'biy^i quadrupeds or whales are 
in the habit oi crossing the real verge, either way, 
however gradual its turn, and however level its ap¬ 
pearance, not even where rivers cross it either way ; 
that in all probability there are no volcanos or maal- 
stroms existing beyond it in the concave ; that the 
length of the degrees ot latitude beyond, are diverse; 
longer in some parts and shorter in others;—that the 
winters beyond the verge in the concave are always 
(comparatively) mild or se\ere, in reverse of ours; 
that the height ot the tides decreases as one passes 
beyond the verge; and that the flood-tide, probably, 
runs one way on the outside of it and the contrary 
way on the inside; and that the tides gradually decline 
towards the temperate inner regions, until they ulti¬ 
mately cease entirely ;§ that the intensity of light de¬ 
creases, particularly for some indefinite distance be¬ 
yond the brow or extreme part of the verge—thatthe 
intensity of gravity gradually increases from the verge 
to the inner equator, in a greater ratio than it increa¬ 
ses from the external equator to the verge; that it is, 
generally, most healthy beyond the verge in the con¬ 
cave, for man, and all other animals, provided they 
are well subsisted; that animals bred within the 
sphere, are prone to pine away and die w hen long re¬ 
moved without; that the temperature of our different 
climates depend upon the distance from the verge, 
and that every climate lies parallel with it, as does 
the magnetic equator; that the winds are more peri¬ 
odical over the slope on this side the north open¬ 
ing than over the slope on the other side; hence, 
perhaps, the monsoon like currents of six months al¬ 
ternate south west and northerly winds may occur, 
which, I contend, Ave experience in America, from 
and towards the north (especially on the plains of 
Missouri) just as the monsoon currents are experien¬ 
ced in India, which currents originate in an inverse 
manner from and towards the south.* 
§ That the variation within the verge is permanent 
while it periodically changes without. 
* These currents of wind could be more consist¬ 
ently accounted for, if admitted to flow towards or 
from the parallel verges ot a narrow er sphere outside 
of the one we inhabit, either in who e oi m part-—i Q 
consequence of alternate suction and protrusion. 
