Remarkable Echoes.
In the gardens of Les Rochas, which was the residence of Madame de Sevigne, is a remarkable echo which finely illustrates the conducting and reverberating powers of a flat surface. The chateau is situated near the old town of Vitre. A broad gravel walk on a dead flat conducts through the garden to the house. In the centre of this, on a particular spot, the listener is placed at the distance of about ten or twelve yards from another person, who, similarly placed addresses him in a low and, in the common acceptation of the term, inaudible whisper, when, "Lo! what myriads rise!" for immediately, from thousands and tens of thousands of invisible tongues, starting from the earth beneath, or as if every pebble was gifted with powers of speech, the sentence is repeated with a slight hissing sound, not unlike the whirling of small shot through the air. On removing from this spot, however trifling the distance, the intensity of the repetition is sensibly diminished, and within a few feet ceases to be heard. Under the idea that the ground was hollow beneath, the soil has been dug up to a considerable depth, but without discovering any clue to the solution of the mystery.
An echo in Woodstock Park, Oxfordshire, repeats seventeen syllables by day and twenty by night. One on the bank of the Lago del Lupo, above the fall of Terni, repeats fifteen. The most remarkable echo known is one on the north side of Shipley church, in Sussex, which distinctly repeats twenty-one syllables. In the Abbey church at St. Albans is a curious echo. The tick of a watch may be heard from one end of the church to the other. In Gloucester Cathedral a gallery of an octagonal form conveys a whisper seventy-five feet across the nave.
In the Cathedral of Girgenti, in Sicily, the slightest whisper is borne with perfect distinctness from the great door to the cornice behind the high altar, a distance of two hundred and fifty feet. In the whispering gallery of St. Paul's, London, the faintest sound is faithfully conveyed from one side of the dome to another, but is not heard at any intermediate point.
In the Manfroni Palace at Venice is a square room, about twenty-five feet high, with a concave roof, in which a person standing in the centre and stamping gently with his foot on the floor, hears the sound repeated a great many times; but as his position deviates from the centre, the reflected sounds grow fainter, and at a short distance wholly cease. The same phenomenon occurs in a large room of the library of the Museum at Naples.