Three minutes later all trace of the Z-5 had disappeared in the dark.

[Sidenote:  Night and day are the same on a submarine.]

Captain Bill of the Z-3 was out on patrol.  His vessel was running submerged.  The air within—­they had but recently dived—­was new and sweet; and that raw cold which eats into submerged submarines had not begun to take the joy out of life.  It was the third day out; the time, five o’clock in the afternoon.  The outer world, however, did not penetrate into the submarine.  Night or day, on the surface or submerged, only one time, a kind of motionless electric high noon, existed within those concave walls of gleaming cream-white enamel.

Those of the crew not on watch were taking it easy.  Like unto their officers, submarine sailors are an unusual lot.  They are real sailors, or machinist sailors—­boys for whose quality the navy has a flattering, picturesque, and quite unprintable adjective.  A submarine man, mind you, works harder than perhaps any other man of his grade in the navy, because the vessel in which he lives is nothing but a tremendously intricate machine.

[Sidenote:  Life on board.]

In one of the compartments the phonograph, the eternal, ubiquitous phonograph of the navy, was bawling its raucous rags and mechano-nasal songs, and in the pauses between records, one could just hear the low hum of the distant dynamos.  A little group in blue dungarees held a conversation in a corner; a petty officer, blue cap tilted back on his head, was at work on a letter; the cook, whose genial art was customarily under an interdict while the vessel was running submerged, was reading an ancient paper from his own home town.

[Sidenote:  News of a German submarine.]

Captain Bill sat in a retired nook, if a submarine can possibly be said to have a retired nook, with a chart spread open on his knees.  The night before, he had picked up a wireless message saying that a German had been seen at sundown in a certain spot on the edge of his patrol.  So Captain Bill had planned to run submerged to the spot in question, and then pop up suddenly in the hope of potting the Hun.  Some fifteen minutes before sundown, therefore, the Z-3 arrived at the place where the Fritz had been observed.

“I wish I knew just where the bird was,” said an intent voice; “I’d drop a can right on his neck.”

[Sidenote:  The sentiments of the captain of a destroyer.]

These sentiments were not those of anybody aboard the Z-3.  An American destroyer had also come to the spot looking for the German, and the gentle thought recorded above was that of her captain.  It was just sundown; a level train of splendor burned on the ruffled waters to the west; a light, cheerful breeze was blowing.  The destroyer, ready for anything, was hurrying along at a smart clip.

“This is the place all right, all right,” said the navigator of the destroyer.  “Come to think of it, that chap’s been reported from here twice.”