152 SEC. 6. SOUND. 



The apparatus itself is, on account of its briltleness, difficult of transport. 

 The glass tubes can be turned by means of metal mountings, and can be 

 displaced in respect of the height of the flames, the largeness of the latter 

 being regulated by small cocks, and the acoustic effect of the major and 

 minor accords (particularly when carefully tuned) are really astonishing. 



695. Diapason Tuning Fork. F. Ernecke, Berlin. 



695a. Diapason arranged for continuous action. 



T. Hawksley. 



696. Tube for Singing Flames, according to Schafi- 

 gotsch's system. . Albrecht, Tubingen. 



697. Set of Glass Tubes for illustrating singing flames, 

 with paper slider for adjusting the pitch of any tube. 



Prof. W. F. Barrett. 



698. Set of Resonant Tubes. Prof. W. F. Barrett. 



By suddenly and successively withdrawing the stopper, the resonance of 

 the air within the series of tubes will give the notes of the common chord. 



699. Apparatus for experiments with singing gas flames. 



YetUe* fy Sons. 



The above, consisting of glass tubes of similar size, with the assistance of 

 a revolving mirror, will illustrate most of the phenomena of interference, 

 harmony, &c. 



700. Inferior Limits of Audibility. An apparatus to 

 show the lowest number of vibrations that will produce sound. 



Elliott Brothers. 



701. Sir Charles Wheatstone's Resonating Tube. 



W. Groves. 



By moving a piston up and down, and thus diminishing or enlarging the 

 resonator, a perfect two-octave scale of aliquot parts may be produced from a 

 spring, which would otherwise sound but one note. The scale may thus be 

 played as rapidly as by the fingers upon a pianoforte. Set the spring in 

 vibration by a twang with the forefinger of the left hand, and draw the piston 

 with the right hand. 



7Ola. Sir Charles Wheatstone's Reciprocating Instru- 

 ment, for rendering the vibrations of rectilinear wires audible at a 

 distance. 



Robert Sabine, 25, Cumberland Terrace, Regent's Park. 



704. Set of five Steel Tuning-forks on a new system. 



Dr. Stone. 



