364 



Messrs. W. H. Preece and A. Stroh. [Feb. 27, 



thing was wanting in their clearness. This instrument proves to be 

 an excellent syren, and all the facts illustrated by the apparatus of 

 Cagniard de la Tour and others can be equally illustrated by it. 

 Moreover, it forms the basis of a new musical instrument which there 

 has been no time as yet to mature. 



18. In the hope of getting more perfect definition, another machine 

 was now made upon which disks were fitted, whose peripheries were 

 •cut in exact copy of the curve produced by the synthetic curve 

 machine. These curves were transmitted by vibration to the receiving 

 diaphragm of a phonograph, and really formed an " automatic phono- 

 graph." The automatic phonograph consists of an axle A, fig. 9, about 

 6 inches long, one end of which carries a fly-wheel B, and the other 

 end a grooved pulley 0, round which a band or gut passes from a 

 driving wheel D, fitted with a crank handle E. On rotating the 

 driving wheel, the long axle is caused to make about three revolutions 

 to one of the wheel. 



On the long axle are placed, in such a manner that they can easily 

 be removed and replaced by others, a number of brass wheels or disks, 

 a, a, a, a, the circumferences of which have been cut by a machine 

 especially devised for that purpose into the different curves corres- 

 ponding exactly to the curves obtained by the synthetic curve machine, 

 but on- a much reduced scale. 



A diaphragm Gr with spring and frame H, similar to that in a phono- 

 graph, is so fitted that it can be shifted from one disk to another, and 

 the sounds produced by the different curves can be readily compared. 

 The number of periods or resultant vibrations recurring on each wheel 

 or disk has for convenience been taken at thirty. Thus, when the 

 driving wheel is rotated about twice per second, 180 to 200 vibrations 

 are caused, resulting in a note at / or g in the musical scale. 



A number of combinations of curves has been cut on the circum- 

 ferences of the brass disks, representing each vowel sound with certain 

 variations of the partials, as experience determined. These disks were 

 then placed on the axle, and the sounds most resembling the vowel 

 sounds of the human voice were easily recognised. 



19. In this way it was found that from about / to b in the musical 

 scale, the sound oo consists mainly of the first partial or prime. But to 

 maintain the oo character descending the scale, the second and third 

 partials became slightly necessary. 



20. The prominent partial in the vowel sound at tlie same pitch 

 is the second, while the first can be reduced considerably. The third 

 and fourth partials have to be used as the sound descends the scale, 

 otherwise what is at say b flat, will become oo an octave lower. 



21. The vowel sound ah is the easiest to reproduce. It consists 

 chiefly of the third, fourth, fifth, and sixth partials at the above pitch, 

 the first and second partials being only slightly represented. A little 



