No. 53 328. 



Dust Figures of Vibrating Air Colums. Tuning Forks. 



435 



53 326. 1 : 7. 



53 328. 1 : 3. 



Tuning Forks and Accessories. 



We give special attention to the manufacture of tuning forks. The forks are, in 

 accordance with the suggestions of the Physikalisch-Technische Reichsanstalt. Char- 

 lottenburg, constructed of solid steel and calibrated against standard forks. The re- 

 sonance boxes are prepared of suitable wood and each box is tuned to the tone of the 

 fork. 



If desired, and on payment of the necessary fees, we send the tuning forks and 

 boxes to the Physikalisch-Technische Eeichsanstalt for test and certificate. The fees 

 are : for a standard fork a x = 435 vibrations, with box, 0. 3. 6 ; for a precision fork a 1 = 435 

 vibrations, with box, 0. 5. 6; transit charges extra. Only those forks having the tone 

 a t = 435 compound vibrations (Ia 3 = 870 v. s.) are certified as Precision Forks. The test 

 fees for forks having a different number of vibrations vary from those quoted above. 



The number of vibrations are given in the following items as whole or compound 

 vibrations, and, in addition (mostly in brackets) as half or simple vibrations, with the 

 French abbreviation "v. s. == vibrations simples". 



The physical pitch is based on the tone c t = 2 s = 256 compound vibrations 

 (ut s = 2 9 = 512 v. s.); the base of the International Pitch being the tone a x = 435 com- 

 pound vibrations (^3-= 870 v. s.). 



53.321. Tuning Fork a! = 435 compound vibrations (Ia 3 = 870 v. s.), with handle, without box 



53.322. Tuning Fork Cj = 256 compound vibrations (ut 3 = 512 v. s.), large pattern, with handle, 

 without resonance box . 



53.323. -- idem, C 2 = 512 compound vibrations (ut 4 = 1024 v. s.) . 



53.324. -- idem, g 2 =768 compound vibrations (so! 4 = 1536 v. s.) . 



53.325. -- idem, c 3 = 1024 compound vibrations (ut 5 = 2048 v. s.) 



53.326. 12 Massive Forks with Stand, after Koenig, Figure (cf. Koenig, Quelques ex- 

 periences d'acoustique, 1882, pp. 102 and 123), c 3 , c 4 , d 4 , e 4 , f 4 , 11 th harmonic of c 1? g 4 , 

 13 th harmonic of c 1? a 4 , 14 th harmonic of c 1} b,, c 5 (ut s , ut 8 , re 6 , mi g , fa 6 , 11 th harmonic 

 of ut 3 , so! 6 ; 13 th harmonic of ut 3 , Ia 6 , 14 th harmonic of ut 3 , si 6 , ut 7 ) 



This set of tuning forks is used for showing that the vibrations of the first and second order become 

 tones if they occur with sufficient intensity. The stand is arranged in such manner that two forks can 

 be clamped for conveniently bowing or striking simultaneously. 



53.327. 4 Tuning Forks, c,, c 5 , c 6 , c 7 , (ut 6 , ut 7 , ut g , ut 9 ), Figure, for demonstrating the 

 limit of audibility 



53.328. Tuning Fork, Figure (W, D. Fig. 258 [244]), of 2000 compound vibrations, for 

 proving Doppler's Theorem 



Cl. 3375, 1125. 



s. d. 



0. 4.0 



1. 0.0 

 0. 18. 

 0. 18. 

 0. 18. 



28.15.0 



2. 8.0 

 1. 10. 



28* 



