Sept. 23, 1 880] 



NA TURE 



489 



The discovery that a musical tone is the result of 

 regularly recurring vibrations, the number of which deter- 

 mines the pilch of the tone, was made by Galileo without 

 any more formal apparatus than a mill-edged coin, 

 along the rim of which he drew his thumb-nail, and found 

 it to produce a sound. We can show this better by 

 taking a common toy gjroscopc-top with a heavy leaden 

 wheel, such as are sold at every toy-shop. With a strong 

 penknife or a file, cut a series of fine notches or grooves 

 across the rim, so that it shall have a milled edge like a 

 coin. Now spin it, and while it spins, gently hold 

 against the revolving wheel the edge of a sheet of stiff 

 writing-paper or of a very thin visiting card. A loud 

 clear note will be heard if the nicks have been evenly 

 cut, which, beginning with a shrill pitch, will gradually 

 fall with a dolorous cadence into the bass end of the 

 scale, and finally die out in separately audible ticks. 



IMuch notice was attracted some years ago by the 

 discovery of singing and sensitive flames. A sensitive 



flame is not easily made, unless'where gas can be burned 

 at a much higher pressure than is to be found in the case 

 of the gas supplied by the companies for house-lighting. 

 To make a singing-flame requires the proper glass tubes 

 and an apparatus for generating hydrogen gas. The 

 roaring-tube, which we are no-,v about to describe, is a 

 good substitute, however, and is also due to the genera- 

 tion of very rapid vibrations, although in this case the 

 way in which the heat sets up the vibrations cannot be 

 very simply explained. Let a common paraflm-lamp 

 chimney be chosen, and let us thrust up loo;ely into its 

 wider or bulbous portion a piece of iron-wire gauze such 

 as is often employed for window-blinds. If this be not at 

 hand a few scraps of wire twisted together, or even a few 

 hair-pins will suffice. The lamp-chimney must then be 

 held over the flame of a spirit-lamp, or other hot flame, 

 until the wire-gauze glows with a red heat (see Fig. 21). 

 Now remove the lamp or lift the chimney oft' it, so that 

 the gauze may cool. It will emit a loud note like a 

 powerful (though rather harsh) organ-pipe, lasting for 



about a quarter of a minute, or until the gauze has cooled 

 Tubes of different sizes produce different notes. 



It is now well known that the quality of difl'erent sounds 

 depends upon the form or character of the invisible sound- 

 waves, and that different instruments make sounds that 

 have characters of their own, because their peculiar 

 shapes throw the air into waves of particular kinds. The 

 different vowel-sounds are caused by putting the mouth 

 into particular shapes in order to produce waves of a 

 particular quality. Take a jew's-harp and put it to the 

 mouth as if you were going to play it. Shape the mouth 

 as if you were going to say the vowel O, and on striking 

 the harp you hear that sound. Alter the shape of the 

 mouth to say A, and the harp sounds the vowel accord- 

 ingly. The special forms of vibration corresponding to 

 the different vowel-sounds can be rendered evident to 

 the eye in a very beautiful way by the simplest con- 

 ceivable means. A sauccrful of soapy water (prepared 



^. 



from yellow kitchen soap and soft water, or with cold 

 water that has previously been boiled) and a brass curtain- 

 ring, is all that is needed. A film of soapy water shows, 

 as °all children know when they blow bubbles, the 

 loveliest rainbow-tints when thin enough. A flat film 

 can be made by dipping a brass curtain-ring into the 

 soapy water, and then lifting it out. When the colours 

 have begun to show on the edge of the film, sing any of 

 the vowels, or the whole of them one after the other, near 

 the film. It will be thrown into beautiful rippUng 

 patterns of colour which differ with the different 

 sounds. Instead of a curtain-ring the ring made by 

 closing together the tips of finger and thumb wfll answer 

 the purpose of providing a frame on which to produce 

 the phoneidoscopic film. 



(.To be continued.) 



GENERAL PITT RfVERS' {LANE FOX) 

 ANTHROPOLOGICAL COLLECTION 



THE collection which General Pitt Rivers, F.R.S., 

 commenced to form in the year 1S51 became well 

 known to all immediately interested in the science of 



