August 8, 1878] 



NATURE 



\97 



One and the same voice, when singing on a or ^, would some- 

 times give the simple and sometimes the duplex form. 



The following general propositions are, we think, established 

 by these experiments : — 



1. The generic character of « from d upwards is given by the 

 prominence of a single partial tone, 'Above If^ this partial is the 

 prime. Below a with certain voices it is the octave of the 

 prime. 



2. The amplitude of the second partial is sometimes as much 

 as nine times greater than that of the prime, but the sound will 

 be recognised as il when the second partial is only three or four 

 times the size of the prime, provided the pitch of the prime is 

 below a. 



3. Below </ the experiments do not warrant positive conclu- 

 sions. The prominence of a single partial is less marked, and 

 at the same time the vowel quality of the spoken sound is very 

 poor. 



4. The average pitch of the reinforced tones is generally lower 

 than the average pitch of the group for 5. 



5. We have not detected any single note having the marked 

 characteristics for il that were possessed by the note b'ty for o. 



6. There is a critical pitch in the neighbom-hood of a or ^, at 

 which a sudden change takes place in the wave- forms given by 

 certain voices in singing il. Further experiments are desirable 

 in this sound at this pitch. The critical pitch is not perfectly 

 constant for a single voice. 



As some doubt may not unnaturally be felt whether or not 

 the singular change of character observed in il at or near the 

 note a may not have been due to some peculiarity of the instru- 

 ment, we may repeat that, being fully aware of this danger, we 

 tried the experiment repeatedly with changed mouth-pieces, 

 changed vibrating disc?, changed springs, and with different 

 thicknesses of tin-foil, but invariably with the residt that certain 

 voices passed at this pitch from the simple to the duplex u. It 

 must not be forgotten, too, that one voice, using the same 

 instrument, carried the simple il as low as/". 



7. This points to the fact that the change from simple to 

 duplex il is not made on account of the requirements of the ear, 

 but on account of the difficulty in adjusting the mouth-cavity so 

 as to continue the simple form on the lower notes. We have 

 seen that, not only do different voices make the change at 

 different pitches, but a single voice gives sometimes one and 

 sometimes the other form at pitches near its critical point. 

 We thus see that the simple and duplex forms overlap, and that 

 in this case sounds of the same pitch, which differ by a whole 

 octave in the pitch of their single prominent tone, are accepted 

 by the ear as generically the same vowel. 



The prominent tone in ft is found to lie in the region from a 

 upwards, but we have not found any one sharply-defined pitch 

 to be characteristic of u. 



With reference to the theory of characteristic tones in vowel- 

 sounds we draw attention to the very great prominence of the 

 tone (5"[) (the characteristic ton? of 0) when voice i sang u or Dy. 

 What may be termed the average pitch in il is for notes near 

 d and e lower than that in o, owing to the absence of the third 

 partial ; but it is noteworthy that, as the voice runs up the scale, 

 the constituents of u are on an average higher than those of for 

 g, and in the case of voice i even for ^ ; this arises from the 

 comparative smallness of the prime. When the simple form is 

 reached the average pitch of the constituents is lower than that 

 for 0. If, instead of looking at the average pitch, we look at 

 the pitch of the highest and most prominent constituent, we 

 find that this pitch is identical for u and when these vowels 

 are sung on g by voices i and 5, and when sung on Hy by 

 voice I. 



Further light is thrown on the whole theory of vowels by 

 experiments on the vowel o as uttered by a mechanical con- 

 trivance made by Prof. Crum Brown and lent by him to us for 

 investigation by help of the phonograph. It consisted of a bag- 

 pipe reed fitted to a tube leading into a gutta-percha resonance 

 chamber which had such a form and such openings (tentatively 

 arrived at) as caused it to speak a very good o when the reed 

 was blown. No one listening to this sound could doubt that the 

 letter o was being distinctly spoken. We held this apparatus to 

 the phonograph, and the record obtained from it gave back a 

 remarkably good o, better indeed than the original, as the jarring 

 noise of the reed was lost. When the pitch of the reed was 

 changed, the same vowel continued to be given. The pitches 

 in our experiments with this resonance bottle ranged from e to /. 

 We had thus a constant cavity producing unmistakably the same 

 vowel throughout an octave. 



Table VII. gives the constituents of each thus artificially 

 produced. They agree with the o's pronounced by the voice in 

 being composed of a prime and its octave for notes above b, also 

 in having the first three partials on e and/i|. On g the third is 

 stronger than in the human voice. No specially strong rein- 

 forcement appears to exist in this artificial for b'^, or any tone 

 near it, but there is a wide range of reinforcement extending on 

 both sides of this pitch. It may be stated that this artificial ^was 

 what might be called a bright o whose pitch of general or of maxi- 

 mum resonance might be expected to be somewhat higher than 

 that of the <7's given by the human voice. 



We draw attention to the fact that even supposing the prime 

 not to have been reinforced at all, this irregular guttapercha 

 cavity must have reinforced tones, more or less strongly, through 

 a range of at least fifteen semitones, namely, from / to g". This 

 fact follows from the analyses, but it was confirmed by another 

 and independent experiment. A short tube was inserted into 

 the bottle in place of the reed and the end of the tube applied 

 to the ear so that the cavity acted as a resonator to sounds 

 from outside. The keys of a piano were then struck in suc- 

 cession and the listener noticed by the bumming noise in the 

 bottle what tones were reinforced. On working down the scale 

 resonance was first noticed at §"0. It increased, and became 

 excessively strong on/", and remained nearly equally strong on 

 e". It then diminished a little, but became very intense again 

 on <r"a, then diminished again, but even on ^ and f'% it was 

 much stronger than could be accounted for by the strengthening 

 of the second partial. Below this the experiment was not suited 

 to detect the influence of the cavity as a resonator on account of 

 the reinforcement of upper partials in the notes struck. It 

 sufficed, however, to prove that this irregular cavity possessed 

 not only one, but probably several proper tones, so near to one 

 another as to give the effect of a resonator strengthening, more 

 or less, every tone between widely distant limits. 



We have also made a few experiments on the vowel sounds 

 "awe " and "ah," which we shall write «° and « respectively. 

 The phonograph spoke these sounds fairly well, though not quite 

 so well as the sounds o and u. It may here be remarked that our 

 phonograph was not capable of registering very high tones ; a 

 shrill whistle, however loud, produced no effect on the tinfoil. 

 This fact proves, independently of the analyses, that in the case 

 of those vowel sounds which it did speak well, the comparatively 

 low partials were sufficient fully to characterise the vowel. The 

 observations show that for a° the first three partials are promi- 

 nent where o has only two ; and that for the same part of the 

 scale a has four consecutive partials all prominent. The fifth 

 partial was considerably strong for a when sung on e, where was 

 composed of three pariials and a" of four. Tables VIII. and IX. 

 show the analyses made of these two vowels as sung by voice 5. 



This communication is already so long that we must defer 

 our general remarks to another number. Fleeming Jenkin 



J. A. EWING 



EXPERIMENTS ON THE RELATIVE SPECIFIC 

 GRA VITIES OF SOLID AND MELTED MA- 

 TERIALS AT THE TEMPERATURE OF 

 FUSION 



T~\R. MUIRHEAD communicates the following account of 

 experiments undertaken at his request, for the purpose of 

 testing the notion that the earth's crxist, as it cooled, became 

 relatively heavier than the molten mass within ; that the crust, 

 breaking into fragments, sank ; and this process, going on time 

 after time, by and by built up a sort of honeycombed arrange- 

 ment of the earth's interior : — 



'^ Railway Works, Leeds, March 30, 1878 

 "Dear Sir, — I have carefuUy gone over the experiments re 

 the melting of metals in contact with liquid metals. I was 

 certain on this point, from more than half a century's observa- 

 tion, before you wrote me, and I think I stated that conclusion 

 in a former letter. I have now only to indicate the order in 

 which I conducted the experiments, the result of which I now 

 communicate. 



" With several different compounds of brass, at various tem- 

 peratures, I melted similar compounds ; skimming the metal in 

 the crucible, I laid the solid piece carefully on the clean surface, 

 which piece, coating itself partially by chilling the liquid metal, 

 very soon re-absorbed a sufficient amount of heat to be fused, 



