the lens and then the shutter was opened, the light admitted for about
one three-hundredth of a second, the shutter closed, and a new section
of film moved into place, while the exposed portion was wound upon a
spool in a light-tight box. The long, flexible film is perforated along
both edges, and these perforations fit over toothed wheels which guide
it down to the lens; the holes in the celluloid strip are also used by
the feeding mechanism. In order that the interval between the pictures
shall always be the same, the film must be held firmly in each position
in turn; the perforations and toothed mechanism accomplish this
perfectly.

In taking the picture of the Suburban race almost five thousand
separate negatives (all on one strip of film, however) were made during
the two minutes five and three-fifths seconds the race was being run.
Each negative was perfectly clear, and each was different, though if one
negative was compared to its neighbour scarcely any variance would be
noted.

After the film has been exposed, the light-tight box containing it is
taken out of the camera and taken to a gigantic dark-room, where it is
wound on a great reel and developed, just as the image on a kodak film
is brought out. The reel is hung by its axle over a great trough
containing gallons of developer, so that the film wound upon it is
submerged; and as the reel is revolved all of the sensitised surface is
exposed to the action of the chemicals and gradually the latent pictures
are developed. After the development has gone far enough, the reel,
still carrying the film, is dipped in clean water and washed, and then a
dip in a similar bath of clearing-and-fixing solution makes the
negatives permanent--followed by a final washing in clean water. It is
simply developing on a grand scale, thousands of separate pictures on