I. SOURCES. 151 



SECTION 6. SOUND. 



WEST GALLERY, UPPER FLOOR, ROOM 



I.SOURCES. 



688. Apparatus used by M. Rijke to cause a tube to emit 

 sounds when wire gauze placed in the interior is heated. 



Professor Dr. P. L. Rijke, Ley den. 



689. Whistles for producing shrill notes, within and beyond 

 the limits of ordinary audition. Francis Galton, F.R.S. 



These whistles were designed for testing the limits of the power of men and 

 animals of hearing very shrill notes. The plugs that close the whistles can 

 be screwed up and down, and the length of the whistle, and therefore the 

 number of vibrations per second, can be ascertained by the attached gradua- 

 tions. The whistles are of three forms : (1) a small cylindrical tube, which 

 gives a pure note, but of small power ; (2) a flat, wide and narrow whistle, of 

 which the plug is a broad thin plate of metal ; (3) an instrument which is 

 externally a cylinder of 2^ inches in diameter, but of which the effective part 

 is merely an annnlus ; the plug of this is a cylindrical sheet of brass ; it gives 

 a powerful note, but not a very pure one. 



690. Brass Tube to sound the constant proper tone of the 

 mouth, characterising the vocal sound. 



Professor Donders, Utrecht. 



This consists of a brass tube ending in a broad slit, at the other end with 

 an india-rubber tube to be placed on a blower " souffleur" (Bonders.) 

 The blast, directed by the slit on the borders of the lips, sounds during the 

 time a vocal sound is sung in different tones, the constant proper tone 

 of the mouth characterising the vocal sound. (Compare Bonders, Uber 

 die Natur der Vocale,_Holl. Beit, zur Nat. u. Heilk. 1846.) 



691. Set of Vowel Forks and Resonance Globes. 



Frederick Guthrie, F.R.8. 



692. Set of Organ Pipes. Frederick Guthrie, F.R.S. 



693. Set of Tuning Forks. Frederick Guthrie, F.R.S. 



694. Photograph of a Chemical Harmonica of glass for 

 gas-flames, with eight pipes (major-scale from d 1 to d 2 inclusive), 

 with double regulating cocks, and key-board for playing. 

 With a copy of a few melodies executed on the same for two 

 and three voices. 



Professor J. Joseph Oppcl, Frankfort-on-the- Maine. 



