Page:The Strand Magazine (Volume 3).djvu/630

 each of the succeeding pictures the leap is carried out, the coat-tails of the rider gracefully rising by degrees. The last of the pictures, just before landing, is probably the only one looking exactly as a painter would represent it. The little spirts and swirls observable about the ground in the first three are the dust disturbed in the gallop and take-off.

Of course in none of these pictures is the moving object absolutely fixed, in the complete and microscopic sense. That would be an impossibility in the case of any continuous motion. In an ordinary slow exposure, should any part of the object move, it is seen with a smeary, misty edge in the resulting picture. Precisely the same thing takes place in every instantaneous picture of a moving thing or things, but the rapidity of the exposure reduces this smeariness to an imperceptible point. Thus if a succession of photographs were taken, say of a trotting horse, giving exposures of one second, th of a second, th, th, th, and th in each case, the pictures would differ thus. In the first the whole thing would be an unrecognisable smudge; the next would be very little better. With th of a second the outline of the horse's trunk would be fairly distinct, unless his pace were great, but the legs would be a fog except any one leg which might be planted upon the ground in the middle of the exposure, and that would be indistinct, because the legs of a smart trotter work very quickly, and his foot is never th of a second upon the ground. With the th the planted leg or legs (legs are not always planted two at a time as the eye tells us) would be fairly sharp, but the others would be blurred, unless the trot were slow or the horse some distance from the camera. The th exposure would be much better—probably a very respectable picture; while the th, of course, all things being favourable, a splendid photograph