the galloping horse, each
photograph taken by an exposure of one fortieth of a second and
separated from the next by an interval of one fortieth of a second.
The horse in Fig. 10 has returned to the same pose as that with which
the series starts in Fig. 1. Fig. 11 gives a pose one hundredth of a
second earlier in the series than that taken in Fig. 2. Fig. 12 shows
a combination of the hinder half of Fig. 9 with the front half of Fig.
6, giving thus the maximum extension of both fore and hind legs.]

It is this duration of the impression on the retina which prevents us
from separating or "seeing distinctly" the successive phases of a
horse's legs as he gallops by, and has led to the remarkable result
that no artist has ever until twenty-five years ago represented
correctly any one phase of the movement of the legs in a galloping
horse, and it is doubtful whether that correctness is what the painter
of a picture really ought to put on his canvas. If we examine the
separate pictures of a galloping horse as taken on a cinematograph
film, we have before us the actual record of the positions assumed by
the legs at intervals of the thirtieth of a second (or whatever less
interval and length of exposure may have been chosen), and it is
simply astonishing to find how utterly different they are from what
had been supposed. Twenty years ago Mr. Muybridge produced a number
of these instantaneous photographs of moving animals--such as the
horse in gallop, trot, canter, amble, walk, and jumping and
bucking--also the dog running, birds of several kinds flying, camel,
elephant, deer, and other animals in rapid movement. The animals were
photographed on a track in front of a wall, marked out to show
measured yards; the time was accurately recorded to show rate
of movement and length of exposure, and of interval between
successive pictures. By means of three cameras worked by electric
shutter-openers, a side, a back, and a front view of the animal were
taken simultaneously. Repeated photographs were obtained at intervals
of a fraction of a second, giving a series of fifteen or twenty
pictures of the moving animal. The length of exposure for each picture
was one-fortieth of a second or less, and the interval between
successive pictures was about the same. Muybridge's great difficulty
had been to invent a shutter which would act rapidly enough. I have
some of these pictures before me now (see Pl. I). They show that what
has been drawn by