โ Scribed by G.F.S.
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The Rehabilitation of the Mines in Northern France. L.
LAttOUSSAY. (La Nature, May I5, '28.) France in I913 used 65,000,000 tons of fuel of which 24,000,000 were imported. The two departments of Nord and Pus de Calais produced two-thirds of all the coal mined in France and employed I3O,OOO workers for that purpose. Unfortunately these departments were soon invaded. Even as early as August, I914, the Anzin mines were lost and by the end of the year two-thirds of this northern coal region was in the hands of the Germans. The lines of battle swayed back and forth over the coal fields of the value of which both sides were fully aware. The Germans had no desire to leave the mines in workable condition and no later than I915 blew up the casings of pits at Lens and Li~vin. Additional destruction was accomplished in I9I 7. A year later they took up the task systematically but had not completed it before they were driven out. The usual procedure was to attach a charge of explosive to the end of a beam just about equal in length to the diameter of the shaft. The beam was lowered and manipulated so that the charge was held between one end of it and the casing. After the explosion had pierced the casing water poured in from adjacent strata and drowned the mine. Of 212 mines in the possession of the Germans I4O were blown up, though not always with the results desired.
In April, I919, a survey of the situation showed that 92,600,000 cu. m., or that number of tons, of water had to be removed from the mines. The greater part of this water was situated at depths ranging from 200 to 400 meters, though some of it was 700 or 800 m. below the surface of the earth. The pumping of this water from intercommunicating mines and its discharge into canals in a country as flat as Flanders presented many problems for solution. Different methods of pumping were used for different levels, and the work of restoring the shafts was undertaken with full recognition of the attendant difficulties. To furnish electric current for the operations it became necessary to erect a central station of I8,OOO kw. capacity.
The removal of the water began in I92O and was at its height in I92I. The mines when finally freed from water had been unworked for periods varying from 5 to I2 years. Their timbers were rotten and their metal parts corroded. In spite of all these drawbacks the production of coal was soon resumed and each succeeding year sees it increasing. In I9I 9 only one per cent. of the pre-war quantity was mined but by I92o it had become 4 per cent. and in I927 Iio per cent. To any one who saw the mines shortly after the war their rehabilitation in so brief a time must appear as a triumph of the engineers of France. G.F.S.
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