458 



Acoustics. 



No. :>:if>76 



53577 (53578). 1:8. 



53583. 1:11. 



53,576. Vibration Microscope, after Weinhold, Figure (W. D. Fig. 239 [225]); can be 

 used at same time as a Topler Vibroscope .......... ........ 



* 53,577. 2 Massive Tuning Forks on Stand for the tone c = 128 compound vibrations ut. 2 = 256 

 v. s.); the pitch of one can be varied by filling with mercury; both with steel mirror and 

 large resonator, Figure (Pogg. Ann. d. Phys. u. Chemie, Vol. 157, 1876, p. 621), for 

 producing any phase differences and impact tones, also for Lissajous's Figures . . . 



One of the two tuning forks hat; both limbs bored out and is provided at the yoke with a screw 

 press by means of which mercury can be forced into the limb. In this manner the frequency can bo altered 

 by 8 compound vibrations ( = 16 v. s.). The resonator of each fork is provided with a i;ap which can he 

 increased or decreased by means of a screw so as to suit its tone to that of the fork. The forks have electro 

 magnetic drive. 



s. d. 

 6. 0.0 



L'7. 10.0 



.">:;, 57S. Variable Tuning Fork c c = 128 compound vibrations alone (iiU -"' v - *) 

 on stand and with variable resonator ........ . . : 



.- u ' (l - 



."i. '..:> T'.i. 2 Tuning Forks with Resonators, same pattern as No. 53.577. but smaller, for i In- 



tone Cj = 256 compound vibrations (ut 3 = 5l2 v. s.) 



19. 5. (i 



21. 0.0 



.>:. :so. Variable Tuning Fork GI = 25(> compound vibrations (ut 3 = 512 v. s.), alone, on stand 



\\ilh variable resonator 



* Can be used with the Projection Apparatus 



15. 10. 



C'l. 1172. 5814, 

 1173, 3381. 



