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Doc. 200.] 577
REPLY TO CELSIUS.
magnet at one place takes place in such regular order, that
the celebrated Halley, of Oxford, has compiled a chart (a
copper-plate of which is also inserted in my work), showing
its deviation, and from which it may be seen that the magnet
does not make such uneven and irregular jumps forward and
backward.
Another consideration that presents itself is this, that if
there actually were a deviation of six hours, as we are informed,
it would be most dangerous for sea -faring people, for in that
case the ship’s course on the ocean would be changed from
side to side every few hours, so as to resemble the course of
those that skate on the ice. From this and several other
arguments and proofs it can be very clearly seen that the
declination and inclination of the magnet always preserves a
’uniformity in its deviation, and that it is caused by the sur
rounding subtle atmosphere which I denominate the purer
ether, and which forms the large vortex of our earth : for if
the perpetually spiral motion of this vortex be examined by
means of a true geometry, it will be found that such a motion
’cannot otherwise than describe its larger and lesser circles,
appoint and locate (utsätta) its centres, and form its axes,
, i. e. form their equator and ecliptic, and together with their
equators and ecliptics form the north and south poles — al
together as this is shown in our system at large, and also
by each magnet on a small scale , when iron powder is
scattered around : for whatever property and natural motion
belongs to a large volume in its atmosphere, or in the atmo
sphere itself, belongs also to a smaller, and even to the small
est volume whenever it is put in motion. From all this,
which is declared and demonstrated by geometry itself and
cannot be disputed, it follows that there can be no other cause
of the declination and inclination of the magnet than the very
vortical fluxion by which our earth is kept enclosed as it were
in its centre; and upon this also my calculation is based. If the
progression of the magnet towards the east or towards the west
was as inconstant as it is declared to be, the earth or our little
world, the existence of which depends upon the constancy of this
system , would most certainly vibrate to and fro in its course,
and would consequently threaten to fall out of equilibrium .
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