The tonnage involved in steel arch construction would be of a much greater order. According to figures quoted by an authority, some 5,200 miles of colliery roadways already in existence have absorbed about one ing a strong, stiff but elastic structure to prevent partial destruction developing into total collapse; strong roofs and floors to avoid delayed explosions and to resist penetration; and weak covering and partition walls to localize explosions and to minimize the danger of flying debris. In addition, steps have to be taken to fireproof inflammable material and to furnish efficient seals against gas or gas poisoned water. AN this means increased steel tonnages.
The new conditions will not induce any radical change in the gener principles of design and construction but that the existing fabricating shops should be able to take up the work without any great capital expenditure on new plant. At the same time, the steel mill: ought to be able to turn out suitable material from existing equipment. Direct armament work, on the other hand, usually calls for costly. specialist equipment in the steel works and manufacturing factories, and often disturbs normal production channels.
Text read from the printed page and cleaned; old type leaves the occasional error.