464- Royal Institution of Great Britain. 



the other end being open, as when it was excited like a flute or fla- 

 geolet, at one end, the other end being shut. In proof of this, he 

 adduced the cremona pipe of the organ, which is a cylindrical tube, 

 one-half the length of the open diapason pipe, which gives the same 

 note; and the clarionet, which is also a cylindrical tube, (the conical 

 bell which terminates it, being merely a useless a])pendage,) giving 

 a fundamental sound, and an octave below that of a flute of eqtial 

 length, and the series of harmonics of a tube closed at one end. He 

 then adverted to the circumstance, that, in all cases of the produc- 

 tion of sound at the closed end of the tube, the tone is invariably 

 more powerful tlian when the sound is produced at the open end of 

 the same tube ; and explained, that in the one case the imi)ulses are 

 made at that part of the air where the condensations and dilatations 

 are greatest, and in the other case where these variations of density 

 are least. This point was illustrated by some experiments with the 

 flame of hydrogen gas, by which means a column of air can be ex- 

 cited into vibration at any point, between the open end and the node, 

 with a corresponding alteration of intensity. At the orifice of the 

 tube, the smallest possible flame is sufficient to excite the sound, 

 which, however, ceases, if the flame be made to move towards the 

 node (i. e. the centre of a tube open at both ends, or the closed end 

 of a tube stopped at one end); but if, at the same time that the 

 flame is advanced in the tube, it be also enlarged in volume, the 

 sound continues, and with increased intensity; by continuing to move 

 the flame towards the node, and at the same time, proportionally to 

 enlarge the volume, the sound progressively increases in loudness, 

 until it attains its maximum at the node. 



Bv analogous experiments on the sounds produced by the flame of 

 hydrogen gas, in tubes of different diameters, Mr. Wheatstone showed, 

 that the loudest tone is produced in tubes of the smallest diameter 

 (when a certain limit is not exceeded), which is exactly the reverse of 

 the o-enerally-adopted opinion ; and he stated tiie following to be the 

 general results of numerous experiments : that the flame is required 

 to be larger, as the length of the tube is greater, as its diameter is 

 less, and as the point of excitation is nearer the node. 



Mr. Wheatstone went on to give an exposition of the laws of the vi- 

 brations of the air, in conical tubes, and explained, that the air in a tube 

 of this form, excited into vibration, at its closed end, or tlie summit 

 of the cone, gave the same fundamental sound, and the same series of 

 harmonics, as a cylindrical tube open at both ends. To this simi- 

 larity of effect, he ascribed the general error, of considering all wind 

 instruments as tubes open at both ends. To illustrate this subject, 

 he showed that the trumpet, Frepch-horn, and haiubois pipes of the 

 organ, all being conical tubes, give the same sound as the cremona 

 pipe fa cylindrical tube, excited' precisely in the same way), which 

 is only one-half their length. iHe compared, also, the haiitbois, 

 which is a conical tube, with a clarionet (which is a cylindrical tube) 

 of the same length, and proved hat, in the former, the fundamental 

 sounds were the same, absolutely and relatively, as in the llute (a 



tube 



