VTH. SPECIAL COLLECTIONS, 167 



759b. Acoustical Instrument, illustrating Harmony 

 and Discord. Sir F. Pichler. 



759c. Violin fitted with Tension Bars. Dr. Stone. 



759d. Viol d'amore, illustrating the principle of consonating 

 springs. " Dr. Stone. 



VIII. SPECIAL COLLECTIONS. 



DETAILED LIST OF INSTRUMENTS MANUFACTURED BY 

 M. LANCELOT OF PARIS. 



Exhibited by Auguste Bel fy Co., London. 



760. Eight Pieces of Wood, giving a scale. 



761. Mouth of a Flute Pipe, showing the inside of the 

 air-chamber. 



762. Wertheim's Apparatus. 



763. Pipe with glass side, and membrane. 



764. Pipe carrying a slide, enabling holes of different sizes 

 and shapes to be opened in the same situation. 



765. Pour Pipes, all containing the same mass of air, one 

 cylindrical, one cubical, one tetrahedral, one spherical. 



766. Three Pipes containing the same mass of air, one pris- 

 matic, one in the shape of a right cone, one in that of an inverted 

 cone. 



767. Mons. Bourbouze's Pipe with glass side, bearing 

 three membranes, with mirror, one placed at the node of the first 

 sound, the two others at the two nodes of the second sound. 



768. Six Plates, five of different woods, one of brass. 



769. Two Plat Bods of brass for transverse vibrations. 

 Support for fixing these. 



770. Sonometer on Mons. Barbereau's principle. 



771. Circular Membranes, with varied tensions. 



772. Two Tuning Forks on resonance box, to give four 

 beats a second. 



773. Two Tuning Forks, mounted between the poles of 

 electromagnets, with contact-breaker. 



774. Duhamel's Vibroscope. 



