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 "My dear sir, I am not aware of any sound, except my great table, which I moved on rising to let you in."

"The table!—let me see that. No, sir; not a tenth part heavy enough, not a tenth part."

"But, sir, you do not consider the laws of acoustics: a whisper becomes a peal of thunder in the focus of reverberation. Allow me to explain this: Sounds striking on concave surfaces are reflected from them, and, after reflection, converge to points which are the foci of these surfaces. It follows, therefore, that the ear may be so placed in one, as that it shall hear a sound better than when situated nearer to the point of the first impulse: again, in the case of two concave surfaces placed opposite to each other—"

"Nonsense, sir. Don't tell me of foci.