The perturbation theory for material replacement experiments is given through second order thus permitting corrections for sample size. Computed flux and adjoint distribution functions are tabulated for the Lady Godiva assembly enabling the observed danger coefficients for U-238 and U-235 to be compared with corresponding predicted values. Consistency of this data is checked by its use in three independent combinations each yielding for the effective fraction of delayed neutrons from fast fission the value L841=0.0068 * 0.0002. Estimation of the reactivity contributions associated with inelastic scattering give the following connection between central danger coefficient ratios and [(%1>~-q~ ratios for the Topsy assembly (oralloy core + 81/2”tuballoy reflector), AK$U-233) A&(U-235) AKO(PU-239) AKJu-235) = 1.71= 1.93 = 1.78. Evaluation of transport cross sections by means of replacement measurements in Godiva is illustrated for the several elements carbon, copper, and gold, the values relative to ~!&(OY) = 1 being ~fi(c) = ().43 f 0.02, ~(CU) = 6.5!5 * 0.02} ~ti(Au) = 0.91 f 0.02.