308 
duced when the front aperture representing the opening of the 
lips is constricted and the vibrating current of air is convergent 
within the mouth and slightly condensed, as shewn by experi- 
ments ; so that another character is given to the sound passing 
the lips, and the vowel-sound U (u) is produced. 
The sound E (e) as in peep is produced when the constriction 
is less than for I (i) and somewhat in front of the back aperture. 
The sound of A (a) open as in papa is produced when the 
front and back apertures are both open. 
The sound of O (0) as in pope is produced when the front 
aperture and part of the shell near it is somewhat constricted. 
The sounds A (a) slender and broad are given by slight ? 
compressions of the hinder hemisphere for the first and of the 
front hemisphere for the latter. 
The whole of the vowel-sounds in their infinite variations 
are thus communicated to a vocal note produced in the larynx 
by the state of the expired vibrating air as it passes through 
the mouth to the external air. 
Professor MAXWELL thought that these experiments could 
hardly be connected with those of Helmholz and Donders, as 
the vowel-sounds differed in different nations. 
Mr Trorrer shewed that what might be called pure vowels 
were very numerous indeed, but that in his opinion 7 was not 
a pure vowel-sound, and he commented upon Helmholz’s in- 
vestigations in the analysis of sounds. 
“Mr SHILLETO observed that he thought that 7 in English 
was always a diphthongal sound. 
Mr FENNELL asked if it was known which of the vowels had 
the greatest and which the least intensity, supposing the funda- 
mental note constant. 
Mr Potter said he thought a (as in father) had the greatest 
intensity, wu (like oo in book) the least, and made some further 
remarks on the subject of the paper. 
Mr H. GoToBeD was elected an Associate of the Society. 
