168 . SEC. 6. SOUND. 



775. Apparatus for transmission of vibrations through 

 liquids. 



776. Instrument for showing the quality of vowel-sounds. 



Various Scientific Instruments illustrating the Phenomena of 

 Sound, invented and made by the late John Henry Gries- 

 bach. 



777. A Monochord, with apparatus for printing and regis- 

 tering the vibrations of strings, with a view to ascertaining the 

 number of vibrations per second. 



778. A Phonometer, by means of which the equally tempered 

 12 fixed sounds in the octave may be produced. 



779. A Monochord, giving the positions of the Nodal Points 

 in vibrating strings. 



780. A Monochord, which affords the means of measuring 

 the 200th part of an inch, with a view to ascertaining the number 

 of vibrations given by that length of string. 



781. An Apparatus for producing musical sounds, mainly 

 consisting of notched wheels of different diameters, which, being 

 set in motion at a given pace, and duly prepared pieces of card- 

 board brought in contact with their teeth, produce the notes of 

 the common chord ; the number of notches in the wheels corre- 

 sponding with that of the vibrations required to produce those 

 notes. 



782. An Apparatus for showing the relative positions of 

 the vibrations of two strings or tubes under the operation of 

 altering the ratios; the strings first tuned to coincidence as 

 unisons, the ratios then altered by lowering the pitch of one of 

 the strings, as from 81 to 80, 82 to 80, or any other numbers 

 within the scale of the apparatus. 



783. A Set of Plue Pipes, with bellows attached, some of 

 which have too high sounds to be heard singly, but which together 

 give the resultant tone. 



784. A large Set of Coloured Diagrams for illustrating 

 lectures on sound. 



785. Collection of Acoustic Apparatus. 



George Appuun and Sons, Hanau. 



