On the magnet, magnetick bodies also, and on the great magnet the earth: a new physiology, demonstrated by many arguments & experiments
History
On the magnet, magnetick bodies also, and on the great magnet the earth: a new physiology, demonstrated by many arguments & experiments
Magnetism -- Early works to 1800
magnetick terrestrial nature which is more prevalent on the greater
continent and not in the aquæous or fluid or unstable part; [219]it follows
that in certain parts there would be a magnetick inclination from the true
pole east or west away from any meridian (whether passing through seas or
islands) toward a great land or continent rising higher, that is, obviously
toward a stronger and more elevated magnetick part of the terrestrial
globe. For since the diameter of the earth is more than 1,700 German miles,
those large lands can rise from the centre of the earth more than four
miles above the depth of the ocean bottom, and yet the earth will retain
the form of a globe although somewhat uneven at the top. Wherefore a
magnetical body is turned aside, so far as the true verticity, when
disturbed, admits, and departs from its right (the whole earth moving it)
toward a vast prominent mass of land as though toward what is stronger. But
the variation does really take place, not so much because of the more
prominent and imperfect terrestrial parts and continent lands as because of
the inæquality of the magnetick globe, and because of the real earth, which
stands out more under the continent lands than under the depths of the
seas. We must see, therefore, how the _apodixis_ of this theory can be
sustained by more definite observations. Since throughout all the course
from the coast of Guinea to Cape Verde, the Canary Isles, and the border of
the kingdom of Morocco, and {154} thence along the coasts of Spain, France,
England, Belgium, Germany, Denmark, and Norway, there lie on the right hand
and toward the east a continent and extensive connected regions, and on the
left extensive seas and a vast ocean lie open far and wide, it is consonant
with the theory (as has been carefully observed by many) that magnetical
bodies should turn slightly to the East from the true pole toward the
stronger and more remarkable elevations of the earth. But it is far
otherwise on the eastern shores of northern America; for from Florida by
Virginia and Norumbega to Cape Race and away to the north the versorium is
turned toward the west. But in the middle spaces, so to speak, as in the
more westerly Azores, it looks toward the true pole. That any magnetick
body turns itself similarly to the same regions of the earth is not,
however, because of that meridian or because of the concordancy of the
meridian with any magnetick pole, as the crowd of philosophizers reckon,
for it is not so throughout the whole of that meridian. For on the same
meridian * near Brazil something very different occurs, as we will show
further on. The variation (cæteris paribus) is always less near the
æquator, greater in higher latitudes, with the limitation that it be not
very near the pole itself. Hence the variation is greater on the coast of *
Norway and Belgium than on the coast of Morocco or Guinea: greater also
near Cape Race than in the harbours of Norumbega or of Virginia. On the
Public-domain text, read in full here on John Shaqi.
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