370 EXPERIMENTS ON THE VIBRATIONS OF PLATES. 



the deepest which the plate is capable of producing. 

 The points at which the plate is fixed or touched must 

 clearly be at rest when the latter vibrates, and hence 

 these points will always be situated in nodal lines. 

 fixing the plate at other points, and touching it in one 01 

 more other places, a great variety of figures maybe pro- 

 duced, of which fig. 219 gives examples; the pom 



FIG. 219 (1 real size). 



touched with the finger are in all cases denoted by a, thos 

 along which the bow is drawn by &, and those where th 

 plate is fixed by c. With a little patience the figure 

 produced with the square plate may be infinitely v 



FIG. 220 (i real size}. 



With a circular plate figures are most easily obtaine 

 which consist of two, three, four or more intersectin 

 diameters, as represented in fig. 220, the letters havin 

 the same meaning as in fig. 219. 



