…

These were the last words I heard.

This wonderful underground conversation, carried on with a distance of four miles and a quarter between us, concluded with these words of hope. I thanked God from my heart, for it was He who had conducted me through those vast solitudes to the point where, alone of all others perhaps, the voices of my companions could have reached me.

This acoustic effect is easily explained on scientific grounds. It arose from the concave form of the gallery and the conducting power of the rock. There are many examples of this propagation of sounds which remain unheard in the intermediate space. I remember that a similar phenomenon has been observed in many places; amongst others on the internal surface of the gallery of the dome of St. Paul’s in London, and especially in the midst of the curious caverns among the quarries near Syracuse, the most wonderful of which is called Dionysius’ Ear.