Mr Glowry was much surprised, on occasionally visiting Scythrop's tower, to find the door always locked, and to be kept sometimes waiting many minutes for admission: during which he invariably heard a heavy rolling sound like that of a ponderous mangle, or of a waggon on a weighing-bridge, or of theatrical thunder. He took little notice of this for some time; at length his curiosity was excited, and, one day, instead of knocking at the door, as usual, the instant he reached it, he applied his ear to the key-hole, and like Bottom, in the Midsummer Night's Dream, 'spied a voice,' which he guessed to be of the feminine gender, and knew to be not Scythrop's, whose deeper tones he distinguished at intervals. Having attempted in vain to catch a syllable of the discourse, he knocked violently at the door, and roared for immediate admission. The voices ceased, the accustomed rolling sound was heard, the door opened, and Scythrop was discovered alone. Mr Glowry looked round to every corner of the apartment, and then said, 'Where is the lady?' 'The lady, sir?' said Scythrop. 'Yes, sir, the lady.' 'Sir, I do not understand you.' 'You don't, sir?' 'No, indeed, sir. There is no lady here.' 'But, sir, this is not the only apartment in the tower, and I make no doubt there is a lady up stairs.' 'You are welcome to search, sir.' 'Yes, and while I am searching, she will slip out from some lurking place, and make her escape.' 'You may lock this door, sir, and take the key with you.' 'But there is the terrace door: she has escaped by the terrace.' 'The terrace, sir, has no other outlet, and the walls are too high for a lady to jump down.' 'Well, sir, give me the key.' Mr Glowry took the key, searched every nook of the tower, and returned. 'You are a fox, Scythrop; you are an exceedingly cunning fox, with that demure visage of yours. What was that lumbering sound I heard before you opened the door?' 'Sound, sir?' 'Yes, sir, sound.' '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. Pray, sir, will concave surfaces produce two voices when nobody speaks? I heard two voices, and one was feminine; feminine, sir: what say you to that?'