Prof. W. Thomson on the Interior Melting of Ice. 303 



the cuticular face assimilates that to the inner one, when the ear 

 exchides hoth tympanic and outer sounds from the labyrinth. Deaf- 

 ness produced by disease in the external meatus only jdelds noises 

 when it propagates irritation so as to excite secretion of mucus on 

 the inner face of the drum-head. Simple perforation of the drum- 

 head only deafens in proportion to the extent of surface removed. 

 If there co-exist a more or less fluid discharge from the drum, this 

 spoils hearing by covering the cuticular surface of the membrane, 

 though it may not deviate so much acoustically from that lined by 

 mucous membrane as to very materially damage it. To remedy such 

 deafness mechanicallj^ we should first essay to rescue the cuticular 

 face from the fluid by placing some material to draw off the discharge 

 from it, so as to keep the membrane fit for its duties, and still ex- 

 posed to aiirial vibrations. If the mischief is so extensive that we 

 are obliged to employ some disc to rest against the remaining ossicles 

 as a substitute for the true membrane, we should try to form one 

 with surfaces acoustically imitating those of the membrane itself. 



The paper concludes by pointing out how the various injuries which 

 have been known to occur by disease or otherwise to the diff"erent 

 parts of the tj-mpanum, are readily accounted for by the functional 

 hypothesis here submitted. 



February 25.— W. R. Grove, Esq., V.P., in the Chair. 



The following communications were read : — 



" Remarks on the interior Melting of Ice." By Professor "William 

 Thomson, F.R.S. In a Letter to Professor Stokes, Sec. R.S. 



In the Number of the ' Proceedings ' just published, which I received 

 yesterday, I see some very interesting experiments described in a 

 communication by Dr. Tyndall, " On some Physical Properties of 

 Ice." I write to you to point out that they afford direct ocular 

 evidence of my brother's theory of the plasticity of ice, published in 

 the * Proceedings ' of the 7th of May last ; and to add, on my own 

 part, a physical explanation of the blue veins in glaciers, and of 

 the lamellar structure which Dr. Tyndall has shown to be induced 

 in ice by pressure, as described in the sixth section of his paper. 



Thus, my brother, in his paper of last May, says, " If we com- 

 mence with the consideration of a mass of ice perfectly free from 

 porosity, and free from liquid particles diffused through its substance, 

 and if we suppose it to be kept in an atmosphere at or above 0° Cent., 

 then, as soon as pressure is applied to it, pores occupied by liquid 

 water must instantly be formed in the compressed parts, in accord- 

 ance with the fundamental principle of the explanation I have pro- 

 pounded — the lowering, namely, of the freezing-point or melting- 

 point, by pressure, and the fact that ice cannot exist at 0° Cent, under 

 a pressure exceeding that of the atinos[)hcre." Dr. Tyndall finds 

 that when a cylinder of ice is placed between two slabs of box-wood, 

 and subjected to gradually increasing pressure, a dim cloudy appear- 

 ance is observed, which he finds is due to the melting of small por- 

 tions of the ice in the interior of the mass. The permeation into 

 jiortions of the ice for a time clear " by the water squeezed against it 

 iVom such parts as may be directly s\ibjccted to the pressure," theo- 

 retically demonstrated by my brother, is beautifully illustrated by 



