Note 7 — LECTURE II THE THEORY OF SPECIAL RELATIVITY
Edwin P. (Edwin Plimpton) Adams translation
Strictly speaking, it would be more correct to define simultaneity first, somewhat as follows: two events taking place at the points and of the system are simultaneous if they appear at the same instant when observed from the middle point, , of the interval . Time is then defined as the ensemble of the indications of similar clocks, at rest relatively to , which register the same simultaneously.