oving under the water consumes electricity, and
the usefulness of a submarine is measured by her electric power.

After fifty-four hours of waking nerve tension, sleep becomes a
necessity. So the ballast-tanks are filled and the nutshell sinks
to the sandy bottom. This is the time for sleep aboard a
submarine, because a sleeping man consumes less of the precious
oxygen than one awake and busy. So a submarine man has three
principal lessons to learn--to keep every faculty at tension when
he is awake, to keep stern silence when he is ashore (there is a
warning against talkativeness in all the German railway-carriages
now), and to sleep instantly when he gets a legitimate
opportunity. His sleep and the economy of oxygen may save the
ship. However, the commander allows half an hour's grace for
music. There is a gramophone, of course, and the "ship's band"
performs on all manner of instruments. At worst, a comb with a
bit of tissue paper is pressed into service.

Another American who suffered an enforced voyage on an
_unterseeboot_ made public later some of his experiences. His
captor's craft was a good sized one--about 250 feet long, with a
crew of 35 men and mounting two 4-1/2 inch guns. She could make 18
knots on the surface and 11 submerged and had a radius of 3200 miles
of action. Her accommodations were not uncomfortable. Each officer
had a separate cabin while the crew were bunked along either side of
a narrow passage. The ventilation was excellent, and her officers
declared that they could stand twenty-four hours continuous
submergence without discomfort, after that for six hours it was
uncomfortable, and thereafter intolerable because of the exudation
of moisture--or sweating--from every part. At such times all below
have to wear leather suits. The food was varied and cooked on an
electric stove. The original stores included preserved pork and
beef, vegetables, tinned soups, fruits, raisins, biscuits, butter,
marmalade, milk, tea, and coffee. But the pleasures of the table
depended greatly on the number of their prizes, for whenever
possible they made every ship captured contribute heavily to their
larder before sinking her. Of the tactics followed the observer
writes:

It appears that 55 per cent., or more than half, of the torpedoes
fired miss their mark, and with this average they seem satisfied.
Once they let go at a sh