jaw drops from its own weight. This will account for the dropping of
the jaw and open mouth of a man stupefied with amazement, and perhaps
when less strongly affected. I have noticed this appearance, as I find
recorded in my notes, in very young children when they were only
moderately surprised.
There is still another and highly effective cause, leading to the mouth
being opened, when we are astonished, and more especially when we are
suddenly startled. We can draw a full and deep inspiration much more
easily through the widely open mouth than through the nostrils. Now
when we start at any sudden sound or sight, almost all the muscles of
the body are involuntarily and momentarily thrown into strong action,
for the sake of guarding ourselves against or jumping away from the
danger, which we habitually associate with anything unexpected. But we
always unconsciously prepare ourselves for any great exertion, as
formerly explained, by first taking a deep and full inspiration, and we
consequently open our mouths. If no exertion follows, and we still
remain astonished, we cease for a time to breathe, or breathe as
quietly as possible, in order that every sound may be distinctly heard.
Or again, if our attention continues long and earnestly absorbed, all
our muscles become relaxed, and the jaw, which was at first suddenly
opened, remains dropped. Thus several causes concur towards this same
movement, whenever surprise, astonishment, or amazement is felt.
Although when thus affected, our mouths are generally opened, yet the
lips are often a little protruded. This fact reminds us of the same
movement, though in a much more strongly marked degree, in the
chimpanzee and orang when astonished. As a strong expiration naturally
follows the deep inspiration which accompanies the first sense of
startled surprise, and as the lips are often protruded, the various
sounds which are then commonly uttered can apparently be accounted for.
But sometimes a strong expiration alone is heard; thus Laura Bridgman,
when amazed, rounds and protrudes her lips, opens them, and breathes
strongly.[1209] One of the commonest sounds is a deep _Oh_; and this
would naturally follow, as explained by Helmholtz, from the mouth being
moderately opened and the lips protruded. On a quiet night some rockets
were fired from the Beagle, in a little creek at Tahiti, to amuse the
natives; and as each rocket, was let off there was absolute silence,
but this was invariably followed by a deep groaning _Oh_, resounding
all round the bay. Mr. Washington Matthews says that the North American
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