Xn. :>3609. 



Sound Interference. Tuning Fork Clock. Phonic Wheel. Mechanical Effects. 



463 



53 605. 1 : 6. 



53 604. 1 : 7. 



53608. 1:5. 



and the eye is directed in such manner that the directly visible upper part of the one flame appears to 

 form the direct continuation of the reflected lower part of the other flame, the image is not disturbed when 

 the tubes of the apparatus are of the same length. If, however, the tube lengths are not equal, phase dif- 

 ferences occur between the two flames and the two -visible halves will appear to be laterally displaced 

 relatively to each other. Tuning fork, resonator and rotating mirror on base are not included in the price. 



51,730. Spark Chronograph after v. Beetz, Figure 51,730, p. 249 



53,604. Tuning Fork Clock after Maudet, Figure, with tuning fork making 64 compound 

 vibrations (128 v. s.) (Koenig, Quelques experiences d'acoustique, p. 173) 



For very accurate determinations of the frequencies of standard forks by comparing the tuning 

 fork clock with a standard clock at different temperatures. The fork is set into vibration and replaces 

 the pendulum of the clock in that it regulates the motion of the clock by means of the escapement; the 

 clock can be also used as a Vibration Microscope. 



s. d. 



7. 10. 

 48. 0. 



for accurately determining the frequencies 



53.605. Phonic Wheel after La Cour, Figure, 



of tuning forks and for similar purposes 



A toothed armature with 20 teeth moves in front of the poles of a horse-shoe shaped multipolar 

 electromagnet. The electromagnet is periodically excited by means of a tuning fork with electromagnetic 

 drive, which opens and closes the circuit. The axis is provided with a counting mechanism which permits 

 of the number of rotations being read off. Exhaustive information as to the manipulation and method 

 of employing the Phonic Wheel may be found in the original work: ,,Das phonische Ead von Paul La 

 Cour", published by Quandt and Handel, Leipsig, 1880. 



The phonic wheel can be driven with a fork making up to 128 compound vibrations (256 v. s.). 



53.606. Tuning fork Jor above, c = 128 compound vibrations (ut 2 = 256 v. s.), with electromagnetic drive for 

 maintaining the vibrations 



Mechanical Effects of Sound. 



53.607. Acoustic Apparatus after Dvorak (Ztschr. f. d. phys. u. chem. U., 6, p. 186), being 

 a selection from the individual apparatus, Nos. 53,60853,610 and 53,613 53,623, 

 listed below 



The smaller apparatus are placed in a containing box. 



The Figure Nos. in brackets relate to Dvorak's article (loc. cit.). 



The experiments are very interesting. 



53.608. Device for Acoustic Attraction and Repulsion, Figure (Fig. 1) 



53,609. Device for Acoustic Attraction and Repulsion for Gases which are lighter than Air 



(Fig. 2) 





7. 10. 



4. 10. 



5.17.0 



0. 3.0 



0. 3.6 



Cl. 5206, 



5760, 1195. 



