Arthur J. Rees, The Mystery of the Downs
“ He commenced to do so, and Marsland wonderingly followed suit. After covering about twenty yards in this fashion Crewe stopped.“That will be sufficient for our purpose,” he said. “Now let us compare the two sets of footprints—the ones we have just made, and the previous ones. Examine them for yourself, Marsland, and tell me if you can see any difference.”Marsland did so. With the mystified air of a man performing a task he did not understand, he first scrutinized the footprints they had made while walking forwards, and then examined the backward ones. ”
