302 



Strehlke on the Acoustic Figures of Plates. 

 For G H G, 



The equation y* = 1-479 . x (x + 5 W< 44), is the expres- 

 sion of the curve A M N. 



The whole figure is consequently composed of hyperbolas of 

 different form, according to the different degree of elasticity at 

 the various parts of the plate. 



It may be easily anticipated what figure will result from the 

 division of the square into nine smaller ones, &c. 



If the plate being supported at D and D' (Fig. 3), and at 

 the middle of F C or C G, the vibration is produced at C, 

 Figs. 9 and 10 will be formed, in which A B is composed of 



Fig. 9. 



Fig. 10. 



Fig. 11, 



Fig. 12. 



A 



two hyperbolas meeting at the centre of the plate. Or, if 

 A and B (Figs. 11 and 12), and a point, which is distant from 

 C or C' by a third of C B, are supported, Figs. 11 and 12 will 

 be obtained, which differs from Figs. 9 and 10 only as far as 

 A B comes nearer a straight line, and that the lines at the 

 corners are almost parts of circles. The tone is for both the 

 same, but that of Figs. 11 and 12 is the fullest of the two. 



