Classes are held at the School of Army Signalling at Aldershot, and from thence the knowledge permeates the Army and the Auxiliary Forces.[84] The requirements are steadiness, intelligence, quickness of eye-sight and of action, and the power to spell correctly; and it takes a man from fifteen to twenty days, at five hours drill a day, to learn the alphabet and the proper manipulation of the flags. The standard of efficiency is ten words a minute with the large flag or sixteen with the small. If our readers will take the trouble to count the letters in the first sixteen words in this present sentence they {129} will find that they are sixty-nine in number, and they will further find, if they take the additional trouble to translate these letters into Morse, that it will take 105 dots and 60 dashes to do it. Our readers will probably then go on to conclude that as it takes one hundred and sixty-five motions of the flag, plus sixty-eight intervals between the letters to signal these sixteen words, a speed of ten words a minute is a very creditable performance either for the sender to work off or for the receiver to read. Besides the ordinary spelling out of the words, various arbitrary signs are used, thus a continued succession of dots ······ is used to call attention to the fact that a message is going to be sent, and a series of dashes ------ means that it is finished. G means "go on," R is a request to "move more to the right" and L to "shift a little to the left"; B means "use the blue flag," and W "use the white flag," K.Q is "say when you are ready," F.I means that figures are coming, and F.F indicates that the figures are finished. Those who have to receive the message may see that the background behind the transmitter is not quite satisfactory for the due observation of the flags, and they may then flash back H or O, meaning either "higher up" or "lower down," as the case may be, and in case of any misunderstanding, they will signal I.M.I, which means "please repeat," and as soon as all is clear, they will signal R.T, meaning "all right." As our man-of-war's-men are also instructed in this system of signalling, communication can be established during an expedition between the ships and the troops on shore. The signal for communication is a white pendant with two black X.X on it. Should this special flag not be forthcoming, the X.X -··--··- (see code of letters) is flashed at night or waved by the flag by day, and as soon as the preparative dots ······ have been acknowledged, the message is dispatched. When the message is of a general character, nothing more need be done, but when it is intended for a particular vessel, the communication is preceded by the special sign apportioned to that vessel.