

THE VIBRATIONS OF HODS. 



round with the finger. If somewhat greater pressure be applied by 

 the bow or the finger, the waves become so much agitated that small 

 drops are detached from their crests and a fine rain of spray is 

 formed over the liquid. If the liquid is alcohol the falling drops 

 remain for an instant upon the smooth portion of the surface 



)efore they disappear in the liquid, and form thus a very pretty 

 ticture, fig. 223. A shallow glass shade with a knob, such as is 

 frequently used for domestic purposes, may be used for the expert 

 nent. The knob is fitted into a hole suitably bored in a small thick 

 )oard and fixed with plaster of Paris. 



Bodies which have the shape of a rod produce various 

 ounds, according to the different modes in which they 

 re fixed, or set to vibrate. The deepest note of a rod 

 uch as a bar of steel, an iron ruler, or a glass tube is 

 btained by holding it at a point which is from Jth to 

 th of its length distant from either end, and striking 

 ith the knuckle of a finger upon the middle or the end 



FIG. 224. 



jfthe rod. The rod vibrates in this case as shown in 

 g. 224, being divided by two nodes into three vibrating 

 igments. 



