" -- Guilielmi Gilberti, Colcestrensis, 'de Magnete
Physiologia nova'. Lond., 1600, p. 40.)
[footnote continues] The absolute depth of the mines in the Saxon
Erzgebirge, near Freiburg, are: in the Thurmhofer mines, 1944 feet; in the
Honenbirker mines, 1827 feet; the relative depths are only 677 and 277 feet,
if, in order to calculate the elevation of the mine's mouth above the level
of the sea, we regard the elevation of Freiburg as determined by Reich's
recent observations to be 1269 feet. The absolute depth of the celebrated
mine of Joachimsthal, in Bohemia (Verkreuzung des Jung Hauer Zechen-und
Andreasganges), is full 2120 feet; so that, as Von Dechen's measurements
show that its surface is about 2388 feet above the level of the sea, it
follows that the excavations have not as yet reached that point. In the
Harz, the Samson mine at Andreasberg has an absolute depth of 2197 feet. In
what was formerly Spanish America, I know of no mine deeper than the
Valenciana, near Guanaxuato (Mexico), where I found the absolute depth of
the Planes de San Bernardo to be 1686 feet; but these planes are 5960 feet
above the level of the sea. If we compare the depth of the old Kuttenberger
mine (a depth greater than the height of our Brocken, and only 200 feet less
than that of Vesuvius) with the loftiest structures that the hands of man
have erected (with the Pyramid of Cheops and with the Cathedral of
Strasburg), we find that they stand in the ratio of eight to one.
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