No. 53220. 



Double Sirens, Wave Sirens, Siren with Blowing Table. 



423 



53 220. 1 : 13. 





53.216. Double Siren after Hebnholtz, driven by a 110 volt D. C. electric motor, Figure, 

 with counting mechanism which when inserted closes an electric contact 



The electric motor has a regulating resistance and a controllable brake device so as to be able 



to adjust the siren to any pitch with certainty. The apparatus is very simple to manipulate. The 



siren is driven by a thin belt, the motor being adjustable so as to keep the belt always taut. In 

 other respects the siren is similar to No. 53,215. 



If a different kind of current or voltage is desired the price is proportionately altered. When 

 ordering kindly state kind of current and voltage for the motor; in the case of alternating and three- 

 phase current the frequency should also be given. 



53.217. Electric Motor alone, with board, adjusting arrangement and regulating resistance 



Cf. the remarks mentioned under the preceding item. 



53.218. Model of the Ship's Siren with concentric, pierced cylinder jackets, the innermost 

 being rotary (Bolte, Leitfaden f. d. Unterr. i. d. Physik an Navigationsschulen, 2 nd Edn., 

 Fig. 108) ; the essential parts, visible through glass, should be placed on the wind chest 



53.219. Large Wave Siren, after Konig, Figure, for investigating sound impulses with 

 wind chest and siren disc the rows of holes of which correspond to the periodicities of 

 the primary tone and the repelled tones 



The apparatus is for showing impulses and impulse -tones produced by the tones of different 

 intervals; the impulses are attained when the rotation is slow and the impulse-tones when the rotation 

 is rapid. A siren disc with holes is used for comparison with the tones produced by the wave siren. 



The curves, which are arranged cylindrically, result from the combination of the two sine curves 

 pertaining to the interval. When a blast is applied a motion of the air results corresponding to that 

 produced by the consonance of two actually simple tones, without any intermingling of overtones. 

 Given in with the apparatus are the waves for the eight intervals 8 : 9 to 8 : 16, and an arrangement 

 is fitted to allow the sirens to sound separately and together. The sirens are actuated by a cord pulley. 



53.220. Blowing Table with Siren, Figure, for demonstration purposes (Model of the 

 German Museum, Munich), siren with Electric Motor Drive; the four rows of holes give 

 the major chord and can be blown either singly or together by using a keyboard. The 

 motor has a regulating resistance so as to be able to raise the fundamental tone an 

 octave, from 256 vibrations to 512 vibrations 



Unless otherwise stated when ordering, we supply the motor for 110 volts Direct Current. 



Cl. 4921. 



d 

 26. 10. 



10. 10. 



2. 10. 



45. 0. 



22. 10. 



