130 Professor Challis's Reply 



In certain dialects of the same language I imagine that 

 <y = Gx- The letter g in the mouth of a native of Berlin, is 

 pronounced (as I am told) intermediately to G and Y.* If this 

 be true, it is in all probability G^. It is probable that in cer- 

 tain dialects, or in certain stages of the Anglo-Saxon, 5 has 



been sounded as Gx. 



* * * * 



Kx then being represented by x, and Gx by y, we have, as 

 an exhibition of the system formed by the sixteen mutes, the 

 following table of double relations. 



s . z . <y . ^ . 



I consider that these relations are immutable and essential, 

 independent of the physiological arrangement, in their forma- 

 tion, of the parts of the mouth and larynx, and independent 

 of their interchanges in the grammars of particular languages. 

 I consider, moreover, that the number of specifically distinct 

 mutes, independent of the fact of their being found in lan- 

 guages, is neither more nor less than sixteen, and that, in the 

 present state of our knowledge, there is no more convenient 

 mode of distinguishing mutes from other articulations, than by 

 saying that every mute is one of four sounds, each of which 

 forms a part of a system of four, and each of which is to some 

 other hard or soft, and lene or aspirate. 



XXV. Reply to Mr. Airy's Remarks on Professor Challis's 

 Investigation of the Motion of a small Sphere vibrating in a 

 resisting Medium. By the Rev. J. Challis, Fkimian 

 Professor of Astronomy in the University of Cambridge. 



To the Editors of the Philosophical Magazine and Journal. 



Gentlemen, 

 A LLOW me, through the medium of your Journal, to ex- 

 -^^ press my thanks to Mr. Airy for calling my attention, by 

 his letter in your Supplementary Number, to a step in my 

 solution of the problem of the resistance to a sphere vibra- 

 ting in an elastic medium, which I had left unexplained. 

 I have certainly considered it possible that the velocity of the 

 fluid at a given distance from the centre to or from which it 

 is directed may, at a given instant, be different in different di- 

 rections from the centre, provided there be no abrupt variation. 



[* The letter g, at least when final, is precisely so pronounced by the 

 Swedes.— Edit.] 



