Page:Popular Science Monthly Volume 91.djvu/593

 Photographing Sunken Ships

A giant electric camera is used for locating sunken ships and treasures

��AN electric submarine camera for deep sea photography has been invented by H. Hartman, a civil engineer of New York city. With it a sunken submarine or a wrecked vessel may be located and pictures of its condition projected for study on a screen in a few hours. Experi- enced divers would re- quire days to secure the same information.

The camera consists of several cylinders con- nected with a steel frame- work. The ball at the bottom is a shock ab- sorber, and the compart- ment above it contains a gyroscope to steady the apparatus against vibra- tion. In the top cylinder is a motor which turns a propeller. This rotates the camera up on its vertical axis so that pic- tures can be taken in all directions. Current for the motor is obtained from above through a cable.

The tank below the propeller cylinder con- tains the camera, as well as the tilting, swinging and focusing apparatus. The shutter and focusing mechanism are both op- erated from separate switches on the surface vessel. A third switch enables the operator to swing the camera in conjunction with the light pro- jector or independently of it. Tests carried out aboard the U. S. S. Vestal proved that the camera could take pictures of the same object repeatedly. Although some were out of focus, the majority were sharp and clear.

Concerning the source of light, which is contained in the largest cylinder of the apparatus, very little is known. Current for the light comes from the surface through a special cable. According to the inventor

���The camera is lowered in the water to any depth up to one thousand feet. The pictures are taken and the entire camera mechanism operated from the surface by means of switches

��the light projector consists of a strong steel cylinder, filled with a gas under varying pressure and having highly con- centrated filaments. The light works on the prin- ciple of the ordinary in- candescent bulb, so far as is known. An inner circle of transparent mica protects the heavy glass lens from the intense heat, although the sur- rounding water reduces the temperature consid- erably. A valve mechan- ism varies the pressure of the gas according to the pressure of the water in which the cylinder is submerged. Reserve gas is contained in a separate compartment. In addi- tion to the live wire which acts as the source of light, there is a flexible steel wire rope to carry the weight of the entire apparatus.

On land the camera mechanism weighs one thousand five hundred pounds. Submerged it weighs about one hun- dred pounds. All parts are tested for a pressure of five hundred pounds to the square inch, which corresponds to a depth of about one thousand feet of water. To operate the light projector and the several small motors, a current of approximately one hundred amperes and one hundred and twenty to one hundred and forty volts is required. When the camera is operating at a great depth under water, the voltage has to be increased to two hundred to make good the loss in passing through the long cable. The inventor proposes to use his camera for treasure hunting, for the locating of sunken ships, and for the study of marine growths. There is no question but what the camera will be of great value in wreck- ing and salvaging operations.

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