In 1877 the maximum annual output for the mines was attained, being $3 6, 3 01, 537.
The output for the year is less than 4000 tons.
Since high average speed on a line with frequent stops depends largely on rapidity of acceleration, the tendency in modern equipment is to secure as great an output of power as possible during the accelerating period, with corresponding increase in weight available for adhesion.
The preceding table shows the average output of the chief coal-groups for the years 1901-1905 inclusive.
The company also owns iron mines, limestone and quartz quarries, large iron-works at Domnarfvet and elsewhere, a great extent of forests and saw-mills, and besides the output of the copper mines it produces manufactured iron and steel, timber, wood-pulp, bricks and charcoal.