When reading messages sent by any "visual" method of signaling, such as flags, heliograph or lamp, it is necessary for the receiver to keep his eyes steadily fixed upon the sender, probably using binoculars or telescope, which makes it difficult, if not impossible, for him to write down each letter as it comes, and as this is absolutely required in military work, where nearly everything is in code or cipher, the services of a second man are needed to write down the letters as the first calls them off. As many letters of the alphabet have sounds more or less similar, such as "S" and "F," "M" and "N" and "D" and "T," many mistakes have occurred. Therefore, the ingenuity of the signaler was called upon to invent names for certain of the letters most commonly confused. Below is a list of the ones which are now officially recognized: A pronounced ack B " beer D " don M " emma P " pip S " esses T " tock V " vick Z " zed The last is, of course, the usual pronunciation of this letter in England and Canada, but, as it may be unfamiliar to some readers, I have included it.