Note 43 — Chapter XII · THE EQUATIONS OF ELECTROMAGNETICS AND LORENTZ’S THEORY

By a first-order experiment, we mean one that is refined enough to detect magnitudes of the order of where is the velocity of the earth through the stagnant ether and is the velocity of light. Likewise, by a second-order experiment, we mean one capable of detecting magnitudes of the order of . Inasmuch as is certainly very much smaller than , is an extremely small quantity, and is very much smaller still. So we see that a second-order experiment is necessarily very much more precise than a first-order one. We may also mention that no experiments have yet been successful in exceeding those of the second order in precision.