21. The cables were placed in ducting throughout the town, and had over 1000 subscribers. 22. The thrust borer laid of ducting through which the mains cable was pulled into position. 23. Ducting influence becomes stronger as frequency drops.24. They drop from parachutes, and climb through air vents and ducting to the lab. 25. In the west wing ducting has been located above a lowered ceiling to the corridor. 26. Elsewhere ducting and plant have been hidden behind walls and in sections of lowered ceiling. 27. The passage and entrance area has a recent lowered ceiling to accommodate air conditioning ducting . 28. This was attached to perforated ducting , which sat on the floor of the silo. 29. Pull the outer covering and the insulation back to expose the inner sleeve of the ducting . 30. Stainless steel ducting would be best.
