Stone had high crushing strength, but in tension it was dangerous.
Standing beneath the cracking dark rock crown at the hundred-foot mark, Giles Croft didn’t reach for wooden timber baulks or steel screw-jacks.
Timber in a deep tunnel was a fire hazard and an upkeep nightmare. Under thirty tons of rock weight, wood groaned, bowed, splintered, and eventually rotted into compost.
“Bring up Segment Car One,” Giles ordered through the speaking horn.
Along the freshly laid narrow-gauge track rolled a specialized low-profile flatcar, pushed by four dwarven trackmen.
Resting on wooden cradles were six curved concrete slabs.
Each slab was five feet wide, nine inches thick. Then he formed into a smooth sixty-degree arc. Steel connection pockets were cast into the matching outward faces. A nonstop channel around the outer edge held a ribbed black rubber sealing seal ring.
Master Mason Orson Briggs walked beside the car, his leather sleeves rolled up. An air-powered impact wrench was resting on his shoulder.
