hat, to an experienced observer,
dressed in furs and taking observations in calm weather, in temperatures
not exceeding say 40 deg. below zero Fahrenheit, the difficulties of the
work resulting from cold alone are not serious. The amount and character
of errors due to the effect of cold upon the instrument might perhaps be
a subject for discussion, and for distinct differences of opinion.

My personal experience has been that my most serious trouble was with
the eyes.

To eyes which have been subjected to brilliant and unremitting daylight
for days and weeks, and to the strain of continually setting a course
with the compass, and traveling towards a fixed point in such light, the
taking of a series of observations is usually a nightmare; and the
strain of focusing, of getting precise contact of the sun's images, and
of reading the vernier, all in the blinding light of which only those
who have taken observations in bright sunlight on an unbroken snow
expanse in the arctic regions can form any conception, usually leaves
the eyes bloodshot and smarting for hours afterwards.

The continued series of observations in the vicinity of the Pole, noted
above, left me with eyes that were, for two or three days, useless for
anything requiring careful vision, and had it been necessary for me to
set a course during the first two or three days of our return I should
have found it extremely trying.

Snow goggles, as worn by us continually during the march, while helping,
do not entirely relieve the eyes from strain, and during a series of
observations the eyes become extremely tired and at times uncertain.

Various authorities will give different estimates of the probable error
in observations taken at the Pole. I am personally inclined to think
that an allowance of five miles is an equitable one.

No one, except those entirely ignorant of such matters, has imagined for
a moment that I was able to determine with my instruments the precise
position of the Pole, but after having determined its position
approximately, then setting an arbitrary allowance of about ten miles
for possible errors of the instruments and myself as observer, and then
crossing and recrossing that ten mile area in various directions, no one
except the most ignorant will have any doubt but what, at some time, I
had passed close to the precise point, and had, perhaps, actually passed
over it.

CHAPTER XXXIII

GOOD-BY TO THE POLE

We turned our bac