May 9, 1878] 



NATURE 



his initial experiments, tracings, and analyses have been con- 

 ducted, lead us to hope that we have at least got an instrument 

 which will enable us to solve the elementary problems of 

 phonetics that have hitherto almost baffled u?, although it is 

 not suited, as yet, to fix those delicacies of utterance which were 

 my own special object of investigation. 

 April 30 Alexander J. Ellis 



On repeating the experiments with the phonograph narra'ed 

 by Mr, A. J. Ellis in Nature, vol. xvii. p. 485, upon 

 a different instrument, I have found the results of my ex- 

 perience to differ in several respects from his. Doubtless 

 each instrument possesses its own individual characteristics ; 

 hence it will be the more needful to exercise caution with 

 respect to generalisation, especially as the existing instru- 

 ments are few and in the hands of few observers. Mr. Ellis has 

 been careful to state the nature of the instrument with which his 

 results were obtained, and the name of Mr. Stroh is a guarantee 

 for the construction of the mechanism. The instrument with which 

 I have been working is of homelier make, and not provided with 

 a driving-train or governor, but simply turned by hand. The 

 same disc — a three-inch ferrotype plate — serves as receiver and 

 transmitter of the voice. The foil used has been, if anything, 

 a little too thin for the purpose. 



On trying the sounds aabaa, aadaa, &c., I found the con- 

 sonants clearly distinguishable, except the sibilants. Aajaa, 

 which is stated by Mr. Ellis to be faultily delivered by the instru- 

 ment, was perfectly recognisable, and could be distinguished from 

 aadaa. Neither was there any confusion between jack and dock 

 or tack; hut Jacques, with the soft /, was sounded out by the in 

 strument as /laak. My phonograph makes the clearest possible 

 difference between the words ioui and ^zV^when carefully spoken, 

 the diphthongal sounds coming cut beautifully as bdaoot and 

 baaeet. On reversing the motion of the handle, tfeadb and tooaab 

 were unmistakable. The double nature of some of our conso- 

 nantal letters is very clearly demonstrated by this process of 

 reversal of motion, as Messrs. Fleeming Jenkin and Ewing 

 have already shown. To the sounds they name let me add that 

 of ch in the word cheque, which we ordinarily pronounce tshek. 

 This word gives a very peculiar sound when reversed in the 

 machine. 



The greatest difficulty— that of getting an instrument to 

 acknowledge the sibilants — is a difficulty that all who have 

 worked with phonograph, phonautograph, or telephone, 

 admit. . The remedy mentioned by Prof. Mayer, that of 

 using a mouthpiece with a very small hole, has the incon- 

 venience of diminishing materially the loudness of the articu- 

 lation of the machine. I have found it better to fasten a strip 

 of card or watchspring across the opening, edgeways, so that 

 the voice impinges on the edge of the strip. With this device 

 sibilants are improved ; the word scissors becomes practicable, 

 though ''Scots" is still intractable. One of Mr. Stroh's instru- 

 ments, which was shown at; the Crystal Palace during Easter 

 week, gave s and 2 fairly. In a familiar phrase the jes are not 

 much missed : Steady, boys, steady, is given with less marked 

 defect of speech than if uttered as thteady, boyih, thteady. 

 Another point of interest that has not, 1 think, been yet 

 mentioned by observers is, that the marks corresponding 

 to the vowel sounds differ when the mouth is at different 

 distances from the vibrating plate, but that yet there is no 

 difference in the vowel subsequently emitted by the machine ; a 

 result which confirms the previously known independence of 

 the vowel sound of the phase of its component partials. For 

 some time I thought my phonograph guilty of dropping 

 its Ks (though not made within the sound of Bow bells), 

 but when that letter is spoken rapidly in a word it is 

 recorded faithfully. Happy land is well heard in the 

 instrument ; and How do you do ? is also aspirated. 

 Cturiously enough, this sentence is spoken almost as well back- 

 wards as forwards (except the aspirate), especially if spoken to 

 the machine with a strong Scottish accent. It is remarkable 

 how useless an instrument without a clockwork regulator is 

 for reproducing even the simplest airs : they are simply lost 

 in noise. Altogether the study of speech by the phonograph 

 is most interesting, and will furnish some most valuable data to 

 students of language and of acoustics. It is impossible to wit- 

 ness its performance without a tribute of acknowledgment to 

 the extreme ingenuity and skill of its inventor, Mr, Edison. 



SiLVANus P. Thompson 



University College, Bristol, May i 



On the Use of the Virial in Thermodynamics 

 The ingenious experiment and the deductions from it, de- 

 scribed by Mr. S. Tolver Preston in Nature, vol. xvii. p. 31, 

 throw a flood of light on the subject of availability of heat-energy, 

 which altogether alters the basis upon which the hitherto imper- 

 fectly expressed conditions of the use of this form of energy will 

 be made to rest Mr, Tolver Preston has, in fact, discovered 

 that discriminating "sprite," or being whom Prof. Clerk-Maxwell 

 imagined ("Theory of Heat," 1875, p. 328) singling out the 

 fast-moving, and separating them in a space by themselves (with- 

 out any expenditure of energy), from the slow-moving molecules 

 of a gaseous mass ; or what is nearly equivalent to this, he has 

 at least shown how some fast-moving and some slow-moving 

 particles of a mass of gas originally in equilibrium, both as to 

 temperature and pressure, zvi/l naturally be so guided amongst 

 each other, that their joint energy will become more available 

 than it was before. But it has, perhaps, not occurred to Mr. 

 Tolver Preston and to some of your readers, that this power or 

 faculty of rendering heat- energy available, which mutual diffusion 

 of heterogeneous gas masses, either through a porous septum or 

 in their own contiguous layers possesses, is a consequence of the 

 general form of efficacy belonging to force, of which Prof. 

 Clausius pointed out the existence in his important propositions 

 on the " virial," ^ as he has ttrmed one of the two members, of 

 which this kind of mechanical tendency of force is the sum. 

 The other member of a force's " radiahty " (as it may be termed) 

 "with respect to a given point," is the vis viva * of the material 

 particle upon •which it acts, in a space of which the selected 

 point is the origin. In description of this newly-discovered 

 natural tendency of a force with respect to a given point or focus,, 

 it is enough to say that while the statical moment of a force, or the 

 product of the distance of its point of application from a point or 

 fulcrum by the resolved part of the force perpendicular to this 

 distance tends to increase uniformly the moment of momentum 

 (defined similarly with that oi force) of the particle upon which it 

 acts, so does the "radiancy" of a force, or the product of the 

 distance of its point of application from a given point or "fccus,'^ 

 together with the vis viva of the particle upon which it acts, tend 

 to increase the "radiancy of momentum" of the particle de- 

 scribed in the same way as the radiancy (or the first term of the 

 radiality) of the force, as just defined. We may speak of the 

 radiancies of equal and opposite reactions, or of force-pairs, in 

 the same way that we deal in statics with the moments of couples ; 

 with similar general properties of their equilibrium, including 

 the resoluticn of the total radiancy (like the impulse, the 

 horse-power, and the moment) of a system of forces, into 

 an internal and an external part wi h respect to the centre 

 of mass of a material system upon which it acts ; and there 

 are principles of conservation of moment and of radiancy of 

 momentum about any point, taken as centre, of all the force-pairs 

 whose moments and radiancies balance each other on a material 

 system. Only the system's vis viva re'"erred to the centre is in 

 the latter case the rate of charge of its radiancy of momentum 

 relatively to it. It is in the same way that the conservation of the 

 motion of the centre of mass, and the conservation of energy, are 

 principles of nullity or of inaction of two other forms of force- 

 agency balancing each other on a material system (the impulse of 

 foices, and the product of their impulse by the virtual velocity of 

 their point of application, or their "horse-power") to which we are 

 obliged to have special recourse to resolve the particular varieties 

 of questions of the " transfer of energy " which occur in mecha- 

 nics. But it is remarkable that the radiality of a force-pair includes 

 the vis viv* of its mass-couplet as one member of its mechanical 

 efficacy, and a surprising example of an agent (evidently the 

 agent cf heat-distribution) here presents itself in which vis viva 

 itself is one of the active elements of the mechanical variation or 

 compulsion ! Its total tendency in any body acted on internally 

 only by directly reacting force-pairs is the total vis viva, and the 

 sum of the virials of these force-pairs, diminished, if the body 

 is subjected externally to a uniform pressure normal to its surface, 

 by three times the we'l known product of this latler pressure by 

 the volume of the bcdy (written -^pv). 



I Poggendorff's Annalen, vol. cxli. (1870), p. 124. But Ciausius, it should 

 te remarked, gives the name " virial " to half oi the quantity which I h»ye 

 described below as the " radiancy " of a force. An exposition of Clausius' 

 new mechanical expression, the virial, with an explanation by its means of 

 the process of condensation of vapours into the liquid state, was given by 

 Prot. Clerk Maxwell in his lecture to the Chemical Society on the molecular 

 theory cf the constitution o'' gaseous and other bodies, in 1875. (See Natubb, 

 vol. xi. p 357 ) 



^ Using this word for ^«7i,v the qrartiiy usv.&lly dcscriled as a particle's 

 "kinetic energy." 



