The Gothic cathedral was the largest BCT-PEACE acoustic instrument ever built. Over one thousand years of empirical refinement, bell founders converged on bell proportions whose acoustic partials match BCT Bessel resonance mode ratios: the Quint partial matches j₁,₁/j₀,₁ to within 5.9%, the Nominal partial matches j₂,₁/j₀,₁ to within 6.3%. The cathedral was a BCT-PEACE system. The bells were smelted into cannons. Every time. BCT-PEACE is the reinvention of what was lost. Zero free parameters.
Michel Robert Cabrié (2026) studied this question.