▁in ▁Manh attan ▁( none ▁of ▁them , ▁including ▁the ▁tall est , ▁the ▁New ▁York ▁Times ▁Building , ▁broke ▁any ▁records ). ▁ ▁The ▁intuit ively ▁simple ▁concept , ▁public ized ▁by ▁the ▁business ▁press ▁in ▁ 1 9 9 9 , ▁has ▁been ▁cross - checked ▁within ▁the ▁framework ▁of ▁the ▁Aust rian ▁Business ▁Cy cle ▁Theory , ▁itself ▁borrow ing ▁on ▁Richard ▁Cant illon ' s ▁eigh teenth - century ▁theories . ▁Mark ▁Thor nt on ▁( 2 0 0 5 ) ▁listed ▁three ▁Cant illon ▁effects ▁that ▁make ▁the ▁sk ys cra per ▁index ▁valid . ▁First , ▁a ▁decl ine ▁in ▁interest ▁rates ▁at ▁the ▁on set ▁of ▁a ▁bo om ▁drives ▁land ▁prices . ▁Second , ▁a ▁decl ine ▁in ▁interest ▁rates ▁allows ▁the ▁average ▁size ▁of ▁a ▁firm ▁to ▁increase , ▁creating ▁demand ▁for ▁larger ▁office ▁spaces . ▁Third , ▁low ▁interest ▁rates ▁provide ▁invest ment ▁to ▁construction ▁techn ologies ▁that ▁enable ▁developers ▁to ▁break ▁earlier ▁records . ▁All ▁three ▁factors ▁peak ▁at ▁the ▁end ▁of ▁the ▁growth ▁period . ▁ ▁Crit ics ▁dismiss ed ▁the ▁sk ys cra per ▁index ▁as ▁an ▁un re li able ▁tool : ▁the ▁post - World ▁War ▁I ▁re cess ion , ▁the ▁re cess ion ▁of ▁ 1 9 3 7 , ▁and ▁the ▁early ▁ 1 9 8 0 s ▁re cess ion ▁were ▁not ▁marked ▁by ▁any ▁record - bre aking ▁projects . ▁Const ruction ▁of ▁the ▁W ool worth ▁Building ▁( world ▁height ▁record ▁