In an paper addressed to linguists and phoneticians it were superfluous to dwell upon the importance of phonetics. All scholars interested in philological research or in modern language instruction must be aware that the teaching of living tongues is greatly improved by a knowledge of phonetics, and that without this science the satisfactory pursuit of comparative philology is impossible. Whatever be the system we adopt in the French and German courses of our colleges and schools, we must admit that pronunciation is an essential element; and the intelligent teaching of pronunciation demands an acquaintance with the physical action by which the sounds of human speech are created and modified. The American teacher, if he have exceptional advantages and an unusually delicate ear, may perhaps be able by mere imitation to acquire a correct foreign accent himself, but neither he nor the foreigner can ever, without a knowledge of phonetics, tell his pupils how to reproduce it. As for the science which we commonly call philology, it consists mainly of the study of sound changes; and the only solid foundation for such study is, obviously, a thorough mastery of the principles of sound-production.