one still clutching his spanner , the other his limb , the pair slid along greased corridors , negotiating bend upon circuitous bend , rattling foot-wide bridges whose rails were razor sharp , tripping through tunnels with no discernible floor , assailed from every quarter by winged beasts that ripped unleavened chunks from thigh and shoulder , smoke wraiths whose favourite trick was to lurk in the abundant mouths and vents of the air-conditioning system and spring noisome ambushes , smothering their pasty miens and so compelling them to run blind , risking a fall , or else stumbling head first into the belching workings of a resident machine .