238 Mr. Willis on the Vowel Sounds, 



that on using a shallower cavity than his, these positions became 

 unnecessary, as a flat board LM sliding on the top of the funnel, 

 and gradually enlarging the opening KL, would give the series 

 U, O, A, just as well, and by making the funnel much shallower, 

 as in Fig. 4*, I succeeded in getting the whole series in the fol- 

 lowing order: U, O, A, E, If. Cylindrical, cubical and other 

 shaped cavities answered as well, under certain restrictions, but 

 I forbear to dwell on this form of the experiment because sub- 

 sequent ones have rendered this more intelligible, and I merely 

 mention it to shew the steps by which I was led from Kempelen's 

 original experiment. 



The success of this attempt induced me to try the effect of 

 cylindrical tubes of different lengths, and for the more complete 

 investigation of this case, I constructed the apparatus represented 

 in Figs. 6 and 7. TF is a tube or portevent bent at right angles, 

 and connected with the wind-chest at the extremity T, this tube 

 terminates in a wooden piston PQ, provided with a socket for 

 the reception of the reed R which is represented in its place. 

 A piece of drawn telescope-tube A BCD is fitted to the piston 

 which is leathered so as to be air-tight, but allows the tube to 

 be drawn backwards or forwards, so as to alter the length of 

 the portion PB beyond the reed at pleasure; the horizontal po- 

 sition is given to the tube to make it more manageable. There 

 are other tubes EFGH of the same diameter as ABCD furnished 

 with sockets at EG which fit on to BD, and their lengths are 

 different multiples o( AB%. 



If therefore any reed be fitted to PQ, and the tube AB be 

 gradually drawn out, it will shew the effect of applying to this 



* Kempelen's funnel is 2 inches diameter at the mouth, and 3 inches deep from the 

 mouth to the reed. Fig. -1, is only 5 inch deep and same diameter. 



t I use these letters throughout with the continental pronunciation. 



J The inside diameter of ABCD =1.3 in., its length = 1 ft. 6 in., and the whole length 

 = 12feet when all the joints are combined. 



