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.
Paulskerk te Londen en vooral onder de merkwaardige holen op Sicilie in de onderaardsche steengroefkerkers bij Syracuse gelegen, waarvan de zonderlingste van dien aard bekend is onder den naam van het oor van Dionysius.