WILLIS'S VOWEL MACHINE. 211 



vowels by sliding a flat board C D over the 

 mouth of the cavity. Mr. Willis then conceived 

 the idea of adapting to the reed cylindrical tubes, 



Fig. 50. 



whose length could be varied by sliding joints. 

 When the tube was greatly less than the length 

 of a stopped pipe in unison with the reed, it 

 sounded I, and by increasing the length of the 

 tube, it gave E, A, O, and U, in succession. But 

 what was very unexpected, when the tube was so 

 much lengthened as to be 1% times the length 

 of a stopped pipe in unison with the reed, the 

 vowels began to be again sounded in an inverted 

 order, viz. U, O, A, E, and then again in a direct 

 order, I, E, A, O, U, when the length of the tube 

 was equal to twice that of a stopped pipe, in 

 unison with the reed. 



Some important discoveries have been recently 

 made by M. Savart respecting the mechanism of 

 the human voice ; * and we have no doubt that, 

 before another century is completed, a Talking 

 and a Singing machine will be numbered among 

 the conquests of Science. 



* See Edinburgh Journal of Science, No. viii., p. 200. 

 P 2 



