100 REPORT — 1839. 



ration was carried quite in a contrary direction : hence the difference 

 in intensity. It was next shown that bronchial respiration, occasioned 

 by solidification of a portion of lung, did not take place in the tubes 

 leading solely to that portion, as had been supposed by Andral and 

 Laennec, because no current of air could take place in tubes whose 

 vesicular extremities had lost their expansibility by which the current 

 was produced ; but that it took place in tubes leading to healthy ex- 

 pansible vesicles ; and the ear being brought into contact with the sides 

 of these tubes, perceived the coarse and comparatively undiverged 

 sound of the air passing and repassing in them. It was contended that 

 no sensible part of the sound of vesicular respiration was produced in 

 or around the vesicles, or by the rubbing of the pleurae, otherwise it 

 would be clearly heard in expiration ; nor in the mouth or fauces, 

 otherwise stertorous breathing would increase its intensity ; that conse- 

 quently it chiefly originated in the bronchial tubes, a supposition ren- 

 dered very probable by the fact, that it is much affected by sonorous 

 and sibilous rales. 



The voice being an instrument of the membranous reed kind. Dr. 

 Blakiston then detailed a series of experiments he had made with dif- 

 ferent kinds of pipes on the wind-chest of an organ, which led him to 

 conclude that the quality of tone of wind instruments became uniformly 

 more coarse and buzzing in proportion to the strength of the blast, and 

 the thinness and elasticity of their sides ; in other words, in proportion 

 as the instrument itself entered into strong vibration. Some curious 

 illustrations of the manner in which interference and jarring was pro- 

 duced between these solid vibrations of the instrument, and those of the 

 air contained in it, were then given, and it was stated that this law was 

 applicable to every wind instrument. Among other instances adduced 

 was that of the flute, in which the upper notes are clear ; and the lower 

 ones, produced by powerful sonorous waves, affecting the material of the 

 instrument, are coarse and buzzing. It was shown that both kinds of 

 vibration were concerned in its formation of the voice, and that hence, 

 when heard over the larynx, it was perceived to be coarse and intense. 

 In proportion, however, as these vibrations travelled downwards toward 

 the air vesicles, they were deadened, the aerial waves by the opposing 

 current of expiration, and the solid ones by the increasing mass of the 

 spongy non-homogeneous lung : hence, at the periphery of the lungs, 

 no resonance of the voice could be detected. 



When however a portion of the lung became solidified, the current of 

 expiration leading from it was stopped, and the spongy lung was trans- 

 formed into a more homogeneous, and therefore better conducting sub- 

 stance : hence the voice resounded strongly, and its quality sometimes 

 became so coarse as to produce a stinging sensation in the ear. Dr. 

 Blakiston stated that he was now employed in investigating the sub- 

 ject of the propagation of sound through different media. 



