Getting Ready (continued)
At its lower end the tube expands into a spherical observation chamber five feet in diameter, one side of which is provided with a large funnel shaped window. This observation chamber is made of cast-iron and weighs four tons. In submarine photographic work two persons usually occupy this observation chamber at the same time, one to take the pictures through the heavy glass window, the other to act as lookout and to give orders to the deck crew overhead. A simple ventilating device freshens the air, so that one may remain below for an indefinite period quite comfortably.
The raising and lowering of the observation chamber is controlled by two chains that are attached to the chamber, and run to chain hoists on the deck, which alter the position of the chamber according to the instructions of the observer below. As the tube is lengthened for deeper and deeper lowering into the ocean, its bottom folds are more and more squeezed together under the increasing water pressure, until, at considerable depths, a section of the tube, that would be eleven feet long when fully extended and would weigh a ton, is compressed into about three feet and still weighs a ton. In other words, through this contraction a given length of tube becomes heavier as it sinks deeper, and this automatic adjustment ensures the proper balancing of the tube in the sea.
The apparatus used by the Williamson Submarine Expedition may appear rather simple in construction, but when it is taken into consideration that it had been perfected only after years of study and experiment, often hampered by difficulties that would have discouraged many; one may get a fair idea of what it meant to the inventor when he discovered that his invention was practical. It had been tested before it was taken to Nassau, but the supreme test of the tube, the chamber, and all the other paraphernalia, came when they took it to strange waters, with the currents of which they were altogether unfamiliar.
It took three or four days for the party to prepare everything for the submarine trip. The first thing that had to be done was to place the observation chamber in position in the shaft, and this was a rather slow process, as the chamber is heavy, and has to be lifted with big steel cranes. Next came the fitting of the heavy glass. This is in one piece, and had to be handled very carefully indeed while it was being fitted to the window. When it was in position, a heavy iron band had to be adjusted over its edge and fastened to the steel grooves on the rim of the chamber, so as to make it absolutely waterproof.
Then came the fitting of the tube, which is made in sections, and is securely fastened together in cork screw fashion. When everything was in place, one of the members of the expedition went down the tube and saw that all was in readiness in the operating chamber for the camera man and the observer. The camera was next placed in position, and the operator and his companion descended the tube, one at a time, with ropes fastened round their waists to guide their descent, and to save them in case their feet should make a false step.
As soon as the signal was given to the deck crew by the observer below, the ship began her journey, moving exceedingly slow in order to give the cameraman an opportunity of taking pictures of the scenes just in front of him on the bed of the ocean.