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580 SWEDENBORG AS A MAN OF SCIENCE. (Doc. 200,
and so forth. On that account also Mr. Graham employed
two needles, placed at some distance from one another, and
he found that they agreed in the hourly variations pretty much
to the same extent. Neither could the friction of the needle
on its pivot be productive of any variation, as Mr. Graham
together with myself established the fact, that when a needle
had reached its greatest or least stage of variation during the
day, and when it was drawn out of its direction by means of
a key, and was kept by means of it in a different direction
from the one it had occupied during the day, after the removal
of the key it nevertheless returned to its former position. It
is sufficiently established thereby that the hourly variation in
the direction of the needle cannot be attributed to a flaw in the
observation, although this is demanded by a certain hypothesis
accepted as true, and it follows also that the cause of this
phenomenon is still unknown to us, and is worthy of being
traced out by more experiments. Meanwhile Mr. Graham has
established by more than a thousand observations that this
variation cannot be ascribed to cold or heat, to a clear or
clouded sky, to a windy or calm state of the atmosphere, nor
to the higher or lower state of the barometer ; which also
agrees with my observations taken here at Upsal. Mr. Graham
also considered himself at liberty to conclude, that the greatest
variation in an increasing ratio usually took place between
12 o’clock at noon and 4 o’clock P.M., and the least variation
between 6 o’clock and 7 o’clock P.M., on which subject I will
communicate the results of my investigations, after I have con
tinued them a little longer.
D.
MAGISTER HIORTER’S145 COMPUTATIONS . *
1. Computation of the magnetic declination for the year
1740, at Upsal, instituted according to the rules laid down by
the most noble Assessor Swedenborg.
* Presented to the Academy of Sciences on January 23, 1741.
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