▁the ▁practical ▁techn ologies ▁of ▁the ▁ 1 9 th ▁century . ▁It ▁had ▁gas ▁light ing , ▁and ▁a ▁warm - air ▁he ating ▁system , ▁which ▁provided ▁fresh ▁air ▁drawn ▁through ▁orn amental ▁stone ▁air ▁in lets ▁below ▁the ▁windows ▁and ▁admitted ▁behind ▁the ▁hot ▁water ▁pip es ▁and ▁' co ils ' ▁into ▁the ▁rooms . ▁War med , ▁fresh ▁air ▁was ▁fed ▁into ▁the ▁st air well s ▁and ▁through ▁h ollow ▁sh aft s ▁within ▁the ▁spir al ▁st air cases ▁to ▁vent il ate ▁the ▁cor rid ors . ▁P ipes ▁supp lying ▁gas ▁for ▁light ing ▁were ▁ingen iously ▁conce aled ▁under ne ath ▁the ▁ban ister ▁rails ▁of ▁the ▁spir al ▁st air cases . ▁Water house ▁designed ▁the ▁building ▁structure ▁to ▁be ▁fire proof , ▁using ▁a ▁combination ▁of ▁concrete ▁and ▁wr ought - ir on ▁be ams . ▁ ▁Ex terior ▁ ▁In ▁mid - 1 9 th - century ▁Manchester , ▁many ▁important ▁Georg ian ▁buildings ▁were ▁black ened ▁by ▁atmos pher ic ▁poll ution . ▁By ▁the ▁ 1 8 7 0 s ▁the ▁local ▁soft ▁red ▁Col ly h urst ▁sand stone ▁was ▁de emed ▁to ▁be ▁un su itable ▁for ▁public ▁buildings , ▁and ▁t ough ▁P enn ine ▁sand st ones ▁were ▁preferred . ▁ ▁The ▁architect ural ▁competition ▁entries ▁were ▁jud ged ▁in ▁part ▁on ▁their ▁suit ability ▁for ▁the ▁" cl imate ▁of ▁the ▁district ", ▁and ▁sample ▁stone ▁types ▁were ▁investig ated . ▁ ▁Water