92 MEANS OF EXPRESSION Chap. IV. 



sary for pouring forth a full volume of sound; but the 

 mouth then assumes, from a quite distinct cause, an 

 almost quadrangular shape, depending, as will hereafter 

 be explained, on the firm closing of the eyelids, and con- 

 sequent drawing up of the upper lip. How far this 

 square shape of the mouth modifies the wailing or cry- 

 ing sound, I am not prepared to say; but we know from 

 the researches of Helmholtz and others that the form 

 of the cavity of the mouth and lips determines the na- 

 ture and pitch of the vowel sounds which are produced. 

 It will also be shown in a future chapter that, under 

 the feeling of contempt or disgust, there is a tendency, 

 from intelligible causes, to blow out of the mouth or 

 nostrils, and this produces sounds like pooh or pish. 

 When any one is startled or suddenly astonished, there 

 is an instantaneous tendency, likewise from an intel- 

 ligible cause, namely, to be ready for prolonged exer- 

 tion, to open the mouth widely, so as to draw a deep and 

 rapid inspiration. When the next full expiration fol- 

 lows, the mouth is slightly closed, and the lips, from 

 causes hereafter to be discussed, are somewhat protruded; 

 and this form of the mouth, if the voice be at all ex- 

 erted, produces, according to Helmholtz, the sound of 

 the vowel 0. Certainly a deep sound of a prolonged 

 Oh! may be heard from a whole crowd of people im- 

 mediately after witnessing any astonishing spectacle. 

 If, together with surprise, pain be felt, there is a tend- 

 ency to contract all the muscles of the body, including 

 those of the face, and the lips will then be drawn back; 

 and this will perhaps account for the sound becoming 

 higher and assuming the character of Ah! or Ach! As 

 fear causes all the muscles of the body to tremble, the 

 voice naturally becomes tremulous, and at the same time 

 husky from the dryness of the mouth, owing to the sali- 

 vary glands failing to act. Why the laughter of man and 



