The nose is the most prominent feature in the face, but as it has scarce any motion, even in the strongest passions, it rather adds to the beauty, than to the expression of the countenance. The form of this feature, and its advanced position, are peculiar to the human visage alone. Other animals, for the most part, have nostrils with a partition between them, but none of them have an elevated nose. Apes themselves have scarce any thing else of this feature but the nostrils, the rest of the feature lying flat upon the visage, and scarce higher than the cheek-bones. This organ serves man and most animals not only to breathe but to enjoy odoriferous scents. Birds have merely two holes for these purposes. The mouth and lips, next to the eyes, are found to have the greatest expression. The passions have great power over this part of the face, and the mouth marks its different degrees by its different forms. The organ of speech still more animates this part, and gives it more life than any other feature in the face. The ruby colour of the lips, and the white enamel of the teeth, have such a superiority over every other feature that they seem to form the principal object of our regard. In fact, the whole attention is fixed upon the lips of the speaker; however rapid his discourse, and however various the subject, the mouth takes correspondent situations, and deaf men have been often found to _see_ the force of those reasonings, which they could not _hear_, by attending to the motions of the lips. Notwithstanding the opinion of Aristotle, with regard to the crocodile, I am convinced, that in that, as well as in man, and other animals, the under jaw alone has the power of motion. In the human embrio, and in monkeys, the under jaw is very much advanced before the upper. In instances of the most violent passion this jaw has often an involuntary quivering motion; and often also pain and pleasure, as well, as languor produces another, which is that of yawning. When the mind is affected with ardent desire, or reflects with regret upon some good unattained or lost, it feels an internal emotion, which acting upon the diaphragm, elevates the lungs, and produces a sigh; when the mind perceives no prospect of relief the sighs are repeated, sorrow succeeds, and tears often follow; the air rushes into the lungs, and gives rise to an inspiration stronger than sighs, termed sobbing, in which the voice becomes more evident; from this it proceeds to groans, which are a species of sobs continued to some length, and are longer or shorter according to the degree of anxiety the mind is labouring under. The plaintive shriek is a groan expressed with a sharp tone of voice; which when violently excited, generally continues the same tone throughout, but when moderate, usually falls at the end.