1835.] Observations on Visible Vibration. 12^ 



These unpleasant sensations were immediately removed by- 

 withdrawing my hand from the bell, which, so long as I 

 ceased to touch, I experienced no inconvenience whatever ; 

 but, on the contrary, a somewhat pleasurable feeling, re- 

 sulting from an apparent sense of a vast number of notes 

 rapidly changing, and as rapidly returning to the same 

 point. The vibration of the bell continued about a minute 

 and a half after the last stroke, and it was quite evident 

 that several notes were produced, besides the fundamental 

 note, which was E flat, within the stave. With the last 

 stroke the octave notes above and below were heard, and, 

 as the sound gradually subsided, the third and fifth harmo- 

 nics were just sensible to the ear. We could not, however, 

 assure ourselves of the relative values of these notes by 

 simply listening, but a few minutes after the hour had 

 struck, we vibrated the bell on various parts of the exterior 

 surface by means of the knuckle and palm of the hand, the 

 result being the production of five different tones, all in 

 perfect harmony with each other, E flat, G, B flat, E flat all 

 in the same octave, and another E flat, at least, two octaves 

 below the fundamental note of the bell ; but these different 

 notes seemed to belong to distinct parts of the bell ; thus, 

 at the lower edge the fundamental E flat was loudest ; the 

 other notes were also heard but in a subdued tone; at about 

 half way up, the G was distinctly brought out, and at the 

 upper part where the vertical sides merge into the horizontal, 

 B flat prevailed ; while close upon the axis we distinguished 

 the upper E flat ; but, in all these instances the major 

 chords of the octave were perceptible, the only difference 

 being found in the circumstance, that different notes predo- 

 minated at different and distinct parts of the bell. We also 

 found that notes in another key could be produced by 

 striking the bell at parts away from those at which the 

 harmonics prevailed ; in this case, single secondary tones 

 could be produced of an isolated character, vague and in- 

 distinct, differing in a marked degree from the pleasing 

 harmonies, as elicited from the four points above described. 

 69. The foregoing explanation will be better appreciated 

 by reference to the following figure : — 



VOL II. 



