130 Captain F. W. Hutton on the Mechanical Principles 



is oblique to the latter — the vestibular aperture being opposed 

 directly to the full stream of the wave, while the cochlear aper- 

 ture is exposed to it obliquely, and, as I apprehend, though I 

 speak less confidently as to this point, laterally with respect to 

 the main stream of the incident wave*. 



The difference of pressure thus occurring at the opposite ex- 

 tremities of the labyrinth will necessarily cause a motion of the 

 stapes outwards, to counteract which the muscle of the stapes 

 will be called into play, so as to produce eventually a motion in 

 the opposite direction — the same action in the labyrinth being 

 thus occasioned which it has already been shown occurs when 

 the ear is in its normal state, and which, I would submit, the whole 

 scheme of the apparatus shows to be essential in order to cause 

 in the human subject the sensation of hearing. 



The question here naturally arises — If, the tympanal mem- 

 brane being absent and the malleus, incus, and Eustachian tube 

 being deprived of all intelligible function, the ear is so compe- 

 tent an instrument for the perception of sound, what can have 

 led to the adoption of the complicated apparatus, the items of 

 which have just been enumerated? 



The consideration of this question, as of other points of the 

 greatest interest connected with the subject, I must reserve to 

 some future occasion. 



6 New Square, Lincoln's Inn. 

 June 22, 1869. 



XIV. On the Mechanical Principles involved in the Sailing Flight 

 of the Albatros. By Captain F. W. Hutton, F.G.S.f 



UNTIL lately no subject in ornithology had been less suc- 

 cessfully treated than that of flight, notwithstanding its 

 great interest. This, no doubt, is owing to the great difficulty of 

 the problem ; for not only has the mechanism of the organs of 

 flight to be perfectly understood, but the complicated question 

 of the resistance of the air to differently shaped surfaces moving 

 with variable velocities must also be more or less completely 

 solved. The first part (i. e. the mechanism of the organs of 



* The assumption that the obliquity of the cochlear fenestra will affect 

 The pressure upon its membrane implies, of course, a variation of pressure in 

 the incident wave according to the direction in which it is estimated. In 

 the March paper above referred to I have shown that when a pulse is pro- 

 pagated along a tube, the vibration being parallel to the axis, a diminution 

 in the pressure exerted on a plane perpendicular to the axis will be due to 

 the velocity. I see no reason to suppose that under the same circumstances 

 any change will occur in the pressure on a plane parallel to the axis. 



f Communicated by Alfred Newton, M.A., F.L.S. &c. 



