divided the Western
hemisphere between Portugal and Spain was not drawn through the most western
point of the Azores, because Columbus wished to convert a physical into a
political division. He attached great importance to the zone (raya) "in
which the compass shows no variation, where air and ocean, the later covered
with pastures of sea-weed, exhibit a peculiar constitution, where cooling
winds begin to blow, and where [as erroneous observations of the polar star
led him to imagine] the form (sphericity) of the Earth is no longer the
same."
The whole of Europe, excepting a small
p 182
part of Russia, has now a western declination, while at the close of the
seventeenth century the needle first pointed due north, in London in 1657,
and in Paris in 1669, there being thus a difference of twelve years,
notwithstanding the small distance between these two places. In Eastern
Russia, to the east of the mouth of the Volga, of Saratow, Nischni-Nowgorod,
and Archangel, the easterly declination of Asia is advancing toward us. Two
admirable observers, Hansteen and Adolphus Erman, have made us acquainted
with the remarkable double curvature of the lines of declination in the vast
region of Northern Asia; these being concave toward the pole between
Obdorsk, on the Oby, and Turuchansk, and convex between the Lake of Baikal
and the Gulf of Ochotsk.
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