BREATHING AND LIVING CONDITIONS UNDER WATER
A submarine conceals within its small compass the most concentrated technical disposition known in the art of mechanical construction, especially so in the spaces reserved for the steering gear of the boat and for the manipulation of its weapons.
The life on board becomes such a matter of habit that we can peacefully sleep at great depths under the sea, while the noise is distinctly heard of the propellers of the enemy's ships, hunting for us overhead; for water is an excellent sound conductor, and conveys from a long distance the approach of a steamer. We are often asked, "How can you breathe under water?" The health of our crew is the best proof that this is fully possible. We possessed as fellow passengers a dozen guinea pigs, the gift of a kindly and anxious friend, who had been told these little creatures were very sensitive to the ill effects of a vitiated atmosphere. They flourished in our midst and proved amusing companions.
It is essential before a U-boat submerges to drive out the exhausted air through powerful ventilating machines, and to suck in the purest air obtainable; but often in war time one is obliged to dive with the emanations of cooking, machine oil, and the breath of the crew still permeating the atmosphere, for it is of the utmost importance to the success of a submarine attack that the enemy should not detect our presence; therefore, it is impossible at such short notice to clear the air within the boat. These conditions, however, are bearable, although one must be constantly on the watch to supply in time fresh ventilation.
Notwithstanding certain assertions in the press of alleged discoveries to supply new sources of air, the actual amount remains unchanged from the moment of submersion, and there is no possibility, either through ventilators or any other device so far known in U-boat construction, to draw in fresh air under water; this air, however, can be purified from the carbonic acid gas exhalations by releasing the necessary proportion of oxygen. If the carbonic acid gas increases in excess proportion then it produces well-known symptoms, in a different degree, in different individuals, such as extreme fatigue and violent headaches. Under such conditions the crew would be unable to perform the strenuous maneuver demanded of it, and the carbonic acid must be withdrawn and oxygen admitted.