INTRODUCTION. 



it is by the help of artificial instruments that music expresses the 

 thought of the composer, that it gives shape to his melodies, and to 

 the harmonies introduced into them to render them more expres- 

 sive and penetrating. From the ancient lyre and harp to the 

 modern violin, to the masterpiece of sonorousness and sweetness of 

 Stradivarius to the powerful organ, so scientifically "built by con- 

 temporary makers, what a numberless variety of musical instruments 

 have by turns lent the help of their tones to musicians of all times 

 and of all countries ! It is true, that it has been by the long and 

 patient researches of the makers, and by the results of experience 

 rather than by the indications of theory, that most of these instru- 

 ments have by degrees acquired their actual perfection. It must 

 be also added that all the conditions of this perfection are far from 

 being scientifically explained. It is not less curious to know how 

 the laws of the sonorous vibrations, which govern the series of notes 

 of the musical scale, are followed and applied in the instruments of 

 the different types, whatever may be the peculiar mechanism of each 

 of them. How many persons play the violin, piano or wind instru- 

 ments without having inquired into the action of the different parts 

 of the instrument which is so familiar to them ; how few know 

 by what mechanism the organist produces that wonderful and 

 powerful collection of sounds which bring before us all the tones 

 with all their various qualities, imitating so exactly all the instru- 

 ments of an orchestra and even the human voice ! 



Here we have an interest, due to curiosity, which will justify 

 the chapters I shall devote to most of the known instruments, by 

 considering them as so many applications of the phenomena and 

 laws of acoustics. This is a novel subject and treated with un- 

 usual length in a work devoted to physics ; yet it is but glanced 

 at, as it would require a volume to give the subject the space 

 which it allows and which it merits. 



IV. 



With Light and the applications with which the study of its 

 phenomena and laws have enriched science, we enter two new 

 worlds ; new, doubtless to those among us who have not studied 



