Worst of all are the waves which break over the periscope, and this prevents a ship from being seen even if it is only a little way off. It is in rough weather that a submarine takes the longest chances; but to put behind him any danger that may be lurking hard by, the captain prefers to run undersea and come to the surface only when he has to. A scheme to clear the moisture from the objective lenses is a device called a _sprayer_. It is made and worked so that an observer at the periscope can spray the lenses with alcohol. As water has a very great liking—or _affinity_, as it is called—for alcohol, and as alcohol evaporates almost instantly it carries the particles of water off with it, and this helps to make the _seeing_ better. =The New Enemy of the Submarine.=—A new enemy of the submarine has recently made its appearance—an enemy that will make it use a periscope of a new order. This latest submarine destroyer is the airplane; and as the captain cannot now see directly overhead except when his boat is running light or awash, and the pilot of an airplane can see the submarine when it is submerged to a very considerable depth, it is easy for him to follow the undersea craft until she comes to the surface and then drop a bomb on her. A story of a running fight between an airplane and a submarine would have put it in Col. Roosevelt’s _Ananias Club_ a few years ago, but to-day it has all come to pass, and it looks now as if a good way to break the backbone of Germany’s ruthless warfare on the sea is to destroy the U-boats with a fleet of airplanes. CHAPTER VIII THE MARVELOUS TONGUE AND EARS OF THE SUBMARINE A Simple Explanation of All the Devices by Which the Submarine Sends and Receives Signals, When on the Surface and Undersea CHAPTER VIII THE MARVELOUS TONGUE AND EARS OF THE SUBMARINE SINCE a submarine has an eye to see with, it is both proper and fitting that it should have a tongue so that it may speak and ears so that it may hear. In fact, an undersea boat is almost human. The early submarine, though, was not only as blind as a cave fish, but it was as deaf and as dumb as a snail; and since this was the case, it had to do whatever talking was necessary by means of a deaf and dumb alphabet, that is, by signaling with flags, or _wigwagging_, as it is called. =The Tongue and Ears of a Submarine.=—The tongue of a submarine—or rather tongues, for it has several—is the fanciful name I have given to the means, methods, and schemes by which messages are sent from one submarine to another submarine or to shore, and the ears are the devices by which it receives messages from other submarines and from shore stations. There are two conditions under which messages must be sent from and received by a submarine, and these are (1) when she is running light or awash, and (2) when she is running submerged.