sufficient experience in
traveling over arctic ice to enable them to estimate a day's journey
very closely. These three were Bartlett, Marvin, and myself. When we
checked up our dead reckoning by astronomical observations, the mean of
our three estimates was found to be a satisfactory approximation to the
results of the observations.

It goes without saying that mere dead reckoning, entirely unchecked by
astronomical observations, would be insufficient for scientific
purposes. During the earlier stages of our journey there was no sun by
which to take observations. Later, when we had sunlight, we took what
observations were necessary to check our dead reckonings--but no more,
since I did not wish to waste the energies or strain the eyes of Marvin,
Bartlett, or myself.

As a matter of fact observations were taken every five marches, as soon
as it was possible to take them at all.

CHAPTER XXIII

OFF ACROSS THE FROZEN SEA AT LAST

The work of the expedition, to which all the former months of detail
were merely preliminary, began with Bartlett's departure from the
_Roosevelt_ on the 15th of February for the final sledge journey toward
the Pole. The preceding summer we had driven the ship through the almost
solid ice of the channels lying between Etah and Cape Sheridan; we had
hunted through the long twilight of the autumn to supply ourselves with
meat; we had lived through the black and melancholy months-long arctic
night, sustaining our spirits with the hope of final success when the
returning light should enable us to attack the problem of our passage
across the ice of the polar sea. Now these things were all behind us,
and the final work was to begin.

It was ten o'clock on the morning of February 22d--Washington's
Birthday--when I finally got away from the ship and started on the
journey toward the Pole. This was one day earlier than I had left the
ship three years before on the same errand. I had with me two of the
younger Eskimos, Arco and Kudlooktoo, two sledges and sixteen dogs. The
weather was thick, the air was filled with a light snow, and the
temperature was 31 deg. below zero.

There was now light enough to travel by at ten o'clock in the morning.
When Bartlett had left the ship a week before, it was still so dark that
he had been obliged to use a lantern in order to follow the trail
northward along the ice-foot.

When I finally got away from the ship, there were in the field, for the
northe