steep places, and at the end you will find us ready to receive you. Now begin moving.”
…
These words cheered me up.
“Goodbye, uncle.” I cried. “I am going. There will be no more voices heard when once I have started. So goodbye!”
…
“Goodbye, Axel, au revoir !”
…
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.
These remembrances came into my mind, and I clearly saw that since my uncle’s voice really reached me, there could be no obstacle between