FIG. 19.—PHOTOGRAPH OF A GULL TAKEN DURING ITS FLIGHT.
| FIG. 20.—ENLARGEMENT OF AN IMAGE TAKEN BY THE PHOTOGRAPHIC GUN. | FIG. 21.—ENLARGEMENT OF ANOTHER IMAGE OF A BIRD TAKEN BY THE SAME APPARATUS. |
The analysis of locomotion in water is one of the most interesting developments of chronophotography. In order to study locomotion in water it was necessary to modify the method. The animals experimented with swam in a glass-sided aquarium fitted in an aperture in a wall, as shown in our [engraving]. The aquarium was directly illuminated by the light of the horizon, forming a very clear field upon which the animals were outlined as silhouettes. Sometimes the external glass of the aquarium was covered by letting down an opaque shutter; then, upon opening another shutter, placed above the water, the brightly illuminated animals were seen standing out from the black field. In most cases it was found necessary to operate before the luminous ground, so it was not possible to receive several successive images upon a removable plate, but it was necessary to cause the sensitized surface to move by starts, so as to bring before the objective points which were always new for each new image that is to be formed. A flexible gelatino-bromide-of-silver film was used. The film was cut into a long and narrow strip which in the camera passed along at the focus of the objective, and unwound from a supply bobbin, and wound around a receiving one.
FIG. 23.—PIGEON RISING IN FLIGHT.
The successive images correspond to less and less advanced phases of the wing’s
revolution.