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698
IX. MINING INDUSTRY AND METAL PRODUCTION OF SWEDEN.
been introduced during the last thirty years, by means of which a still more
exact and more detailed knowledge of the magnetic conditions can be obtained.
These instruments are: the magnetometer constructed by Professor TliaUn, of
Uppsala University, on the Lamont principle, also the vertical power balance
quite lately constructed by Prof. Thalén on the principle of Lord Kelvin (Sir
William Thomson), and the Tiberg inclinator or inclination-balance. Everywhere ia
our mining-districts the magnetometer and inclinator have been used with the
best results, both above ground and in the mines. There is doubtless not a
single iron mine of any consequence in all Sweden where these instruments have
not been used in one way or another, and there are magnetic map» of a very
large number of mines based on measurements made with the one or the other of
the aforesaid instruments. This has enormously facilitated the work of exploring
and prospecting. When guided by the results of the magnetic measurements, it
has been rendered possible to direct this work much more exactly than would
otherwise have been possible, and there has been a great saving of gallery and
shaft excavations and other kinds of exploring and prospecting work. Even for
determining the value of smaller ore-fields, measurements are made with these
instruments and magnetic maps are laid out.
Magnetic instrument. Combination of the Thalén and Tibebg ones.
What has been said above in regard to the magnetometer and inclinator,
will doubtless be said in the future in regard to the newest magnetical instrument,
or the vertical power balance.
The mining compass is little known in other countries. About 1866,»
similar compass was invented in America. The magnetical instruments invented
by Thalén and Tiberg are still little or not at all known in other countries.
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