By means of this sketch, the message may often be shortened, for the sender can refer by letter or number to various points on the sketch, whereas he would otherwise be compelled to describe positions or to go into detail at length. When he does draw a sketch, he should refer to it somewhere on the bottom of the face of the message thus: (See sketch over) or (See sketch reverse side). The sketch is not usually duplicated. The reverse side of the message blank appears thus: [Illustration: (grid of 25x35 squares) _Scale of Sketch_ ... _ins. = 1 mile._ _When scale is 6 ins. = 1 mile, each small square is 50 yards._ _When 3 ins. = 1 mile, each one is 100 yards._ _When 6 ins. = 1 mile, V.I. = 10 ft. When 3 ins. = 1 mile, V.I. = 20 ft._] The form of address of the regulation envelope for this message appears below. It is probably best explained by an extract from paragraph 36, Field Service Regulations, which reads as follows: “Messages carried by a messenger are usually enclosed in envelopes properly addressed. The envelope when not marked ‘confidential’ is left unsealed, so that commanders along the line of march may read the contents. Upon the envelope is written the name of the messenger, his time of departure, and rate of speed. The last is indicated as follows: Ordinary, rapid, or urgent. Ordinary means five miles an hour for a mounted man; rapid, about 7 or 8 miles an hour; and urgent, the highest speed consistent with certainty of arrival at destination. The recipient notes the time of receipt upon the envelope and returns the latter to bearer.” UNITED STATES ARMY FIELD MESSAGE _To_..................................... _No_........... (For signal operator only.) ----------------------------------------------------------- _When sent_.............................. _No_........... _Rate of speed_.......................................... _Name of Messenger_...................................... _When and by whom rec’d_................................. =This Envelope Will Be Returned to Bearer= We should certainly be armed with a Field Message Book when the crucial moment for writing a message arrives. But it so happens, especially in open warfare, that that article of equipment may have been left in the saddlebags, or have been borrowed by a friend. At any rate it is not present for duty when we want it. However, we are always able to produce a piece of paper or clothing—something upon which to write—from someone of the party present. It behooves us, then, to learn to compose a message without the aid of a blank. Indeed, this idea is contained in the latter part of the quotation from the Infantry Drill Regulations—“and the form therein adhered to.”