Freely Falling Clocks

@article{Armstrong1973FreelyFC,
  title={Freely Falling Clocks},
  author={H. L. Armstrong},
  journal={Nature},
  year={1973},
  volume={244},
  pages={26-26}
}
SURELY Ellis1 has not really answered Dingle's question. For the question was: “Which of the two …”; not: “Which of all possible …”. Suppose that neither of the clocks was in free fall.