Full resolution (JPEG) - On this page / på denna sida - Second part - IX. Mining Industry and Metal Production - 1. The Iron Mines (together with information regarding other mines). By the late Prof. O. G. Nordenström - Technics of mining
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technics op mining.
705
Mining Alidade.
produced to the State Mining Official on demand; and the other is to be forwarded
to the Oßce of Mine Maps, a division of the Board of Trade at Stockholm,
irhere there is thns deposited a complete collection of all the mine plans in the
country — a collection quite unique, no other country having anything similar.
It iB also prescribed that in all mines which are being worked every new piece of
work must be surveyed
and mapped, at the latest,
before the end of the
year after it is begun,
and it is the mine-owner’s
duty to forward these
supplementary surveys to
the Office of Mine Maps,
whereby the collection of
plans at this office is
fully supplemented from
year to year, and kept
exactly like those
preserved at the mines.
In order still better to
illustrate the geological
and other conditions of
the mines, it has for a
long time been usual to
make models of the mines; but it is
only during the last thirty years that
these models have been carried out in a
manner fully suitable for the purpose.
The models are of two types.
When a model is to be made of a
mine with, at the most, 6 to 8 levels,
the contours of the working areas and
the geological conditions of each level
are painted in oil-colours on glass plates,
all in conformity with the normal map.
Then these glass plates are placed one
above the other, and at a distance from
each other exactly in proportion to the
distance between the different levels
represented, and so that each glass will
have a perfectly exact position in relation
to the others.
If, on the other hand, a model is
to be made of a mine with a larger
number of levels, the aforesaid type of
mine-models cannot be used, but then
the following method must be resorted to. The different levels are cut out of
stiff white pasteboard, on which the ores, etc., are marked with the respective
colours. Then these sections are fastened on squares of wire stretched on wooden
frames, which are placed the one over the other so that each will have its exact
position in relation to the others.
Both of these model types are very practical, and give a clear idea of the
position of the working areas in relation to each other, the mode of occurrence
of the ore, and the other geological conditions of the mine.
Sweden. 45
Mining Plain Table.
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