s have to be carefully
husbanded, sleep is dangerous unless frequently broken, and if one of
the party breaks down, the strength of the whole is seriously
diminished, while its task is greatly increased. Such has been the
history of exploration up to within 400 miles of the pole, and it is at
least probable that many of these difficulties will be intensified as
that point is reached. The north pole may now be considered to occupy
the centre of an area 800 miles in diameter, the condition of things
within which it is not possible even to conjecture. We may plausibly
suppose (1) that it is not land, for the ice of the Arctic sea is never
more than 150 feet thick, and there are no glaciers; (2) that it is a
shallow sea; and (3) that the precipitation of moisture in the centre
must be considerable, as the ice is moving in all directions from the
centre during the summer. The theory of an open sea at the pole is now
discarded by most scientific men, and, we believe, by all experienced
explorers except Hayes. In the present state of knowledge it rests upon
the presumption that the polar sea is very shallow, so that the deep
and warm currents which are known to enter the Arctic ocean may be
forced to the surface there; and that the ice drift removes the ice as
fast as it forms.

EXPLORATION NOTES.

THE Portuguese government has decided to spend $100,000 on a
scientific expedition to Central Africa.

EVERY exploring expedition across the continent of Australia has to
taste the extreme difficulties of travel in the barren parts of that
extraordinary country. Mr. Giles, the last explorer, says: "From the
end of the watershed in longitude 120 deg. 20 min., the latitude being
near the 24th parallel, to the Rawlinson range of my last horse
expedition, in longitude 127 deg., the country was all open spinifex
sandhill desert. At starting into the desert most of the camels were
continually poisoned, the plant which poisoned them not being allied in
any way to the poison plants of the settled districts of Western
Australia. I now know it well, and have brought specimens. The longest
stretch without water was a ten days' march. One old cow camel died
after reaching the water. We had some rain on May 8 before reaching the
Ashburton, and some of it must have extended into the desert. It was
the only chance water we obtained."

PROF. NORDENSKIOLD, who sailed from Norway to the mouth of the river
Jenesei, in Siberia, is now