Louisa here remarked that she had often heard of some very extraordinary echoes in different parts of the world, to which her father had not alluded; she mentioned, for instance, those which are said to repeat the same sound several times in succession. “From the explanation which I have already given of the nature of echoes,” said Mr. Seymour, “it will be easily conceived that a vast variety of effects may be produced by varying the form, the shape, the distance, and the number of reflecting surfaces: and hence we hear of various surprising echoes in different places. It is not difficult, for instance, to understand the nature of compound, or tautological echoes; in which case the expression of one _ha_ will appear like a laughter. Addison mentions an extraordinary instance of this kind near Milan, which will return the sound of a pistol fifty-six times.” “I have understood that the echoes on the lakes of Killarney are of this multiplied description,” said the vicar. “They are particularly calculated to produce reflections of sound, from the height of the mountains, and the expanse of water,” replied Mr. Seymour, “which latter circumstance always assists the conveyance of reflected, as well as direct sound. I believe that there is a certain spot on the shore of Ross island, where the sound of a bugle produces an echo which far exceeds any other to be met with amongst the lakes; the first echo is returned from the castle, the second from the ruined church of Aghadoe, the third from Mangerton, and afterwards innumerable reverberations are distinguished, which, like the faded brilliancy of an extremely multiplied reflection, are lost by distance and repetition.” “There is an admirable echo,” said the vicar, “behind my old college at Cambridge; and often have I, while walking on the road to Chesterton, on a calm evening, distinctly heard twelve repetitions of the voice. Lord Bacon, if I remember correctly, mentions an instance of sixteen, in some ruined church near Paris.” “It was in the church of Pont-Charenton, on the Seine,” replied Mr. Seymour; “in which place that great philosopher discovered the inability of an echo to return the letter S, for having pronounced the word _satan_, the echo replied _va-t-en_, which in French signifies _away_; from which circumstance, the Parisians concluded, that some guardian spirit prevented the walls of the sacred edifice from pronouncing the name of _satan_.” “And will not an echo repeat the letter S?” asked Louisa. “Not always,” answered her father; “the hissing or sibilant noise of the letter, when at the commencement of a word, is generally lost, unless the echo be extremely perfect.”