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Isotope abundance, nuclear separation energies, spin and nuclear magnetic moments supply complementary tests: abundance concerns which atomic nuclei survive and accumulate, removal energy concerns binding, and magnetic properties test the angular momentum assignments. Agreement across these observables is more informative than fitting one list of numbers.

In her 1963 lecture, Maria Goeppert Mayer recalled excess abundances at $N=50$ and $82$. She contrasted the strong binding of the last neutron in oxygen isotope ${}^{16}\mathrm{O}$ with the weaker extra neutron in oxygen isotope ${}^{17}\mathrm{O}$, and displayed beta decay energies near $N=20$ and $50$. These are compiled empirical patterns, rather than readings from an apparatus she built.^[ref]

Her 1949 letter compared observed spins and nuclear magnetic moments with orbital assignments. For example, lead isotope ${}^{207}\mathrm{Pb}$ was assigned a $p_{1/2}$ neutron hole near $N=126$, whereas bismuth's odd proton began the next shell as $h_{9/2}$. The moments tested orbital character as well as spin.^[ref]

A useful comparison holds $Z$ fixed when comparing neighboring isotopes, and examines odd-even staggering separately from a shell discontinuity. Abundance additionally depends on production and decay history. Neither the abundance pattern nor a successful spin assignment directly images orbiting particles; neither fixes a unique nuclear mean field. The experimental techniques themselves include mass spectrometry and nuclear magnetic resonance, whose preparation and readout differ. The Hofstadter nuclear electron scattering experiment separately constrains nuclear size and nuclear charge distributions, rather than measuring these occupancies.

Pressure calibration assigns pressure values to a sensor's output by comparison with a reference under specified conditions. It is not the same as making the output more finely resolved. A smooth electrical resistance curve can be repeatable yet have an incorrect pressure scale.

Bridgman used pressure-dependent electrical resistance of manganin and established fixed points, including a bismuth transition. He reported poorer accuracy above the better calibrated range.^[ref]

A fixed-point specimen and a property-measurement sample have distinct roles: one helps assign the scale, while the other is studied on that scale. The reference transition must itself have an assigned pressure at the relevant temperature. Agreement at a single point does not determine a nonlinear sensor response elsewhere. Comparing increasing and decreasing pressure checks hysteresis; returning to a reference checks drift. These are checks one can design from the measurement model, not additional historical controls asserted for the lecture's experiments.