200 LETTERS ON NATURAL MAGIC. 



produced by waves or undulations in an ethereal 

 medium, filling all nature, and occupying the 

 pores of transparent bodies, the successive pro- 

 duction of sound and silence by two loud sounds, 

 or of light and darkness by two bright lights, may 

 be explained in the very same manner as we 

 have explained the increase and the obliteration 

 of waves formed on the surface of water. If 

 this theory of light be correct, then the breadth 

 of a wave of red light will be the 258th 

 thousandth part of an inch, the breadth of a wave 

 of green light the 207th thousandth part of an 

 inch, and the breadth of a wave of violet light 

 the 157th thousandth part of an inch. 



Among the wonders of modern skill, we must 

 enumerate those beautiful automata by which the 

 motions and actions of man and other animals 

 have been successfully imitated. I shall therefore 

 describe at present some of the most remarkable 

 acoustic automata, in which the production of 

 musical and vocal sounds has been the principal 

 object of the artist. 



Many very ingenious pieces of acoustic mecha- 

 nism have been from time to time exhibited in 

 Europe. The celebrated Swiss mechanist, M. le 

 Droz, constructed for the King of Spain the figure 

 of a sheep, which imitated in the most perfect 

 manner the bleating of that animal ; and like- 

 wise the figure of a dog watching a basket of 

 fruit, which, when any of the fruit was taken 

 away, never ceased barking till it was replaced. 



The singing-bird of M. Maillardet, which he 

 exhibited in Edinburgh many years ago, is still 

 more wonderful.* An oval box, about three 



* A similar piece of mechanism had been previously 

 made bv M. le Droz. 



