38 COMPARATIVE LANGUAGE 



grammar. These speech-sounds are molecular vibrations produced 

 by the organs of speech and perceived by the organs of hearing. 

 The historian of language must know something of the nature and 

 mechanism of these organs, of the organic and acoustic character of 

 the sounds, of the processes or more often combination of processes 

 involved in their changes. The branch of science which deals with 

 such matters, known as practical phonetics or the physiology of 

 sound, is an application of physiology and physics to linguistic 

 material, and in its latest development, experimental phonetics, has 

 reached a degree of refinement never suspected as possible. Direct 

 visual observation, which can be employed only to a limited extent, 

 is supplemented by mechanical devices of all sorts, ranging from the 

 simple artificial palate, upon which is marked the exact position and 

 area of the tongue contact, to the various instruments used to record 

 the manifold vibrations of a vowel, from which a curve of vibration 

 is plotted, the extent of each vibration measured in millimetres and 

 transferred by a formula to time measurement to the hundred thou- 

 sandth of a second. In many cases the knowledge gained experi- 

 mentally is of undoubted interest and value to the historian of lan- 

 guage. On the other hand, some of the experimental investigations 

 are so refined that one cannot conceal one's skepticism as to their 

 availability for the history of language. Certainly they go beyond 

 the present interest of linguistic students and appeal more to phys- 

 icists and physiologists. "The physical definition of a vowel will 

 consist of the mathematical expression for the course of the mole- 

 cular vibrations which it involves" are the words of one of the 

 principal exponents of experimental phonetics in this country. The 

 comparative grammarian cannot yet foresee the time when his com- 

 parison of vowels will be so minute as to be based on a study of 

 their vibration curves, even if this were not impossible for any lan- 

 guage not actually spoken to-day. Yet he should be the last to 

 depreciate any investigations which deal, from whatever point of 

 view, with the material which is his chief concern. 



The Relation of Comparative Grammar to Psychology 



The advent of comparative grammar and the historical method for- 

 ever put an end to the role which speculative philosophy had so long 

 played in linguistic discussions, from the time of the Greeks, who 

 debated the origin and nature of speech while still ignorant of even 

 the crudest analysis of the forms of their own language, to the gram- 

 moire generate or universal grammar of the eighteenth century, to 

 Gottfried Hermann, who decided that the number of original cases 

 must have been six, as in Latin, corresponding to Kant's categories 



