388 Scientific Intelligence. 



ments are fully described and a large number of curves given in 

 a series of plates at the end of the volume. The careful analysis 

 of these curves leads to a number of most interesting and impor- 

 tant results, and enables the author to arrive at a definite conclu- 

 sion upon several controverted points, such as the action of the 

 vocal cords, the theory of vowel sounds, the melody and rhythm 

 of speech, the duration of long and short vowels, etc. In regard 

 to the action of the vocal cords, the opinion is strongly main- 

 tained that they do not vibrate like stretched strings or mem- 

 branes, but, at least in the chest register, act by alternately open- 

 ing and closing the orifice between them, somewhat (one would 

 judge) in the manner of a striking reed blown from the wrong 

 side ; the mechanics of such a vibration is not altogether obvi- 

 ous, but, puttnig aside this difficulty, the hypothesis makes the 

 cord tone consist of a series of puffs of air similar to those pro- 

 duced by a siren, and more or less explosive in character. Many 

 of the curves appear to support this view. One of the conse- 

 quences, however, which the author draws from this theory, and 

 insists upon repeatedly (pp. 41, 94, 97, 263, etc.), cannot be 

 accepted : it is that the cord tone, since it consists of such a series 

 of explosive puffs, cannot therefore be resolved into simple har- 

 monic (sinusoidal) constituents by the use of Fourier's Theorem. 

 As a matter of fact, a series of explosive increments and decre- 

 ments of the air pressure can be expressed by a Fourier expan- 

 sion, even when the rise and fall are assumed to take place really 

 instantaneously, that is, in a mathematically infinitesimal time, 

 and for however small a fraction of the interval between two 

 puffs the increased pressure endures; if the puffs are all alike 

 and occur at equal intervals of time, then the lowest term in the 

 Fourier series w^ill have a frequency equal to the number of puffs 

 in a second ; if they are not all similar the series will begin with 

 a term of lower frequency, but in any physical case there can be 

 no doubt that the expansion is possible, and any argument based 

 upon the supposed non-harmonic character of the cord-tone will 

 be fallacious. The convenience and utility of such an expansion 

 in any given case is another question. In the discussion of the 

 vowel sounds, some confusion is introduced by this erroneous 

 assumption ; but much experimental evidence is adduced in sup- 

 port of the theory of Willis, according to which the resonance 

 tones characteristic of each vowel are fixed in pitch and have no 

 necessary relation to the cord tone, and against Helmholtz's 

 theory that the resonance tones are always harmonies of the cord 

 tone. 



Taken as a whole. Dr. Scripture's work is distinctly interesting 

 as well as instructive ; it is written with spirit and enthusiasm, 

 the illustrations are admirable, and the descriptions of apparatus 

 and of experimental methods are so clear and detailed that it 

 might well serve as a laboratorj^ manual. To the student of 

 phonetics it will of course be indispensable on account of the 

 w^ealth of scientific material which it contains. h. a. b. 



