M.4NUAL POR NONCOMMISSIONED OFFICEES. 811 



exactly north, the deviation is, from a military point of view, 

 slight, and appreciable error will rarely result through the 

 use of the magnetic instead of the true north in the solution 

 of any military problems. 



Should you be curious to know the exact deviation, consult 

 your local surveyor or any civil engineer. 



Both arrows may appear on your map. In that case disre- 

 gard the magnetic arrow unless you are using the map in 

 connection with a compass. 



If a map is being used on the ground, the first thing to be 

 done is to put the lines of the map parallel to the real outlines 

 of the ground forms, and roads, fences, railroads, etc., that the 

 map shows; for the making of a map is no more than the 

 drawing on paper of lines parallel to and proportional in 

 length to real directions and distances on the ground. 



For instance, the road between two places runs due north 

 and south. Then on the map a line representing the road will 

 be parallel to the arrow showing the north and will be propor- 

 tional in length to the real road. In this way a map is a pic- 

 ture, or better, a bare outline sketch ; and, as we can make out 

 a picture, though it be upside down, or crooked on the wall, 

 so we can use a map that is upside down or not parallel to the 

 real ground forms. But it is easier to make out both the pic- 

 ture and the map if their lines are parallel to what they repre- 

 sent. So in using a map on the ground we always put the 

 lines parallel to the actual features they show. This is easy 

 if the map has an arrow. 



If the map has no arrow, you must locate objects or features 

 on the ground, and on the map, their representations. Draw 

 on the map a line connecting any two of the features; place 

 this line parallel to an imaginary line through the two actual 

 features located, and your map will be correctly placed. Look 

 to it that you do not reverse on the map the positions of the 

 two objects or features, or your map will be exactly upside 

 down. 



When the map has been turned into the proper position — 

 that is to say, " oriented " — the next thing is to locate on the 

 map your position. If you are in the village of Easton and 

 there is a place on the map labeled Easton, the answer is 

 apparent. But if you are out in the country, at an unlabeled 

 point that looka like any one of a dozen other similar pointi, 



