These were the first underwater photos to reveal the ocean floor—in full color
Capturing the first underwater color photographs was no mean feat and involved powerful explosives as well as hours and hours of waiting.
The following illustrations are the first published natural color photographs made beneath the surface of the sea. They represent many weeks and months of experimentation by Dr. W. H. Longley, noted ichthyologist, of Goucher College, and Charles Martin, of the photographic laboratories of the National Geographic Society.
The conditions encountered off Dry Tortugas, of the Florida Keys, necessitated the development of a special technique for this unique photographic undertaking, because the ordinary autochrome plate would not register the moving life under water. It was necessary to hypersensitize all plates used in shallow depths, so that the under-sea exposures might be reduced to a twentieth of a second.
Owing to the dampness, the excessive heat, and the lack of sufficient power at Dry Tortugas to operate an electric fan properly, the sensitizing had to be undertaken each morning at 5 o'clock (the coolest time of day), to prevent the emulsion on the glass plates from melting.
Flashlight powder supplements sunlight for depth pictures
When the scientists attempted to make autochromes at depths of as much as 15 feet, it was found that, owing to the greatly reduced power of sunlight, even the hypersensitized plate would not give satisfactory results. It became necessary to supplement and intensify the sunlight. Mr. Martin, therefore, constructed a flashlight-powder mechanism which could be discharged by the submerged photographer at the exact moment of his finny subjects' best posings. The additional illumination made possible autochromes on plates which had not been hypersensitized.
One problem which had to be solved was to synchronize the discharge of the flash-light powder with the camera shutter, so that the latter would be wide open at the instant that the flash had reached its illumination peak.
A pound of magnesium powder was used for every charge. The ignition of such an amount of dazzling explosive on a dory piloted by two men, who were forced at the same time to follow the shadowy movements of the diver with his camera far below, was more than human nerves could stand. Especially was this true when it sometimes happened that the men in the boat had to wait for two or three hours, every moment anticipating the blinding and deafening detonation. They could never know at what instant the diver would find his quarry in the desired position with respect to his lens.
To overcome this nerve-racking suspense, three small pontoons were constructed to support a dry-cell battery, the flash-light powder, and the reflector. The contrivance, floating upon the surface and guided here and yon, could be handled by the diver himself, leaving the men in the dory free to follow their colleague under sea at a safe and comfortable distance from the powerful explosive, yet near enough to maintain the necessary flow of air pumped to the man beneath the surface. The mere setting of the electrical connections, however, within a few feet of the big charge of powder was a hazardous undertaking.
On one occasion Dr. Longley was seriously burned and incapacitated for six days by a premature explosion of an ounce of powder. Had it been a full charge, the accident would probably have been fatal or resulted in permanent blindness.
The camera used in making these autochromes was inclosed in a brass case with a plain glass "window" in front of the lens. A supplementary hood was fitted above the regulation reflector, and by means of an acute-angle mirror the photographer was able to focus his instrument, looking directly in front of him instead of bending over the camera—a movement which would have been extremely difficult while wearing the diver's helmet.
By untiring effort and patience came success in a new field of natural-color photography.
(These images will help you see coral reefs in a whole new way.)
