INSTRUMENTS FOE EXPERIMENTS ON SOUND. 145 



get by striking it across, but you hear also intensely high 

 upper partial notes which sound very persistently, so that 

 even in this large room it will be possible to hear an exces- 

 sively high note above the range of the highest piccolo that 

 ever sounded ; and it will continue for several seconds after 

 the blow. If the bar or rod be supported at more than 

 one point it forms the usual harmonicon. "We have here 

 two very remarkable instruments of this character; one is 

 on the plan of a musical-box. It is very singular that this 

 should have been contrived so well by a half-savage tribe 

 in Angola, that you can get a perfect scale out of it; the 

 bars of metal are supported at one end on a resonance-box 

 of wood, there are also feathers under them, but they are 

 connected with some fetish superstition. Passable music 

 might have been got out of this. Here is another which I 

 find in the Exhibition, which may be recognised as one of the 

 various attempts at wood harmonicons. These instruments 

 have been formed of all sorts of things, of wood, stone, glass, 

 and metal. A clever little boy was brought forward some 

 years since to play what was called a " xylophone," which con- 

 sisted of pieces of hard wood ; on which he really performed 

 very creditably. Then there was the "rock harmonicon" 

 which I can remember in my early days, and the glass har- 

 monicon you must know very well The one I show is a 

 wood harmonicon. It is formed by adding resonators of 

 a very ingenious kind to bamboo blocks. One of these has 

 unfortunately been broken in carrying it over, but that same 

 accident enables us to look at the mechanism. The resonators 

 are formed of gourds or calabashes, outside which is put a 

 little ear-trumpet to act the function of the pinna of the 

 human ear, to collect the sound ; in the hollow of this I 

 discover a small membrane, a piece of thin material resembling 

 goldbeater's skin, intended to reinforce the sound. Here then 

 is one of the last discoveries of Helmholtz anticipated and 

 utilized in the wildest parts of Africa. We have other more 

 developed forms of this instrument, such as the musical-box, 

 which is excited by mechanism. We have the vibrating bar 

 partially producing the sound in the Jew's-harp, and regulating 

 the vibration of a column of air in the harmonium. The 

 form I wish to speak of to-day is the tuning-fork. 



Tuning-forks form a great portion of the experimental 

 apparatus of acoustics. They may be looked upon simply 



VOL. II. L 



