134 THK APPLICATIONS OF PHYSICAL FORCES. [BOOK n. 



in drum cylinders. Drums can be tuned a whole octave by various 

 contrivances for straining the membrane. 



Kettle-drums are a species of drums in which the skin is stretched 

 over a metal box rounded underneath : they are used in the cavalry. 

 The drummer carries this double drum on either side behind the 

 pommel of his saddle, and he strikes it with balls covered with 

 leather; in this way they give out a more agreeable sound than if 

 they were struck with an ordinary drumstick. 



These instruments have been introduced into our orchestras, but 

 care is taken to tune them to a third or some other musical interval, 

 by constructing them of different sizes, and by stretching the skin 

 more or less tightly. 



The drum is a very ancient instrument, and under diversified 

 forms, widely spread in civilised and barbarous countries. The 

 tambourine, used in village fetes in Provence, is an elongated drum 

 which the performer beats with one hand, accompanying himself on 

 a little three-holed flute. One of the most original forms of the 

 drum is that of the Japanese tambourine represented in Fig. 89. 

 This is the hing-kou ; he performer strikes the skin with two sticks ; 

 the instrument rests on a double stand or foot, which prevents the 

 vibrations from being dulled by the ground. 



