FM 3-25.26 MAP READING AND LAND NAVIGATION

tick marks in between are not used (Figure 5-5C).h. There may be times when the distance you measure on the edge of the paper exceeds the graphic scale. Inthis case, there are different techniques you can use to determine the distance.(1) One technique is to align the right tick mark (b) with a printed number in the primary scale, in thiscase the 5. You can see that from point (a) to point (b) is more than 6,000 meters when you add the 1,000meters in the extension scale. To determine the exact distance to the nearest 10 meters, place a tick mark(c) on the edge of the paper at the end of the extension scale (Figure 5-6A). You know that from point (b)to point (c) is 6,000 meters. With the tick mark (c) placed on the edge of the paper at the end of theextension scale, slide the paper to the right. Remember the distance in the extension is always read fromright to left. Align tick mark (c) with zero and then measure the distance between tick marks (a) and (c).The distance between tick marks (a) and (c) is 420 meters. The total ground distance between start andfinish points is 6,420 meters (Figure 5-6B).Figure 5-6. Determining the exact distance.(2) Another technique that may be used to determine exact distance between two points when the edgeof the paper exceeds the bar scale is to slide the edge of the paper to the right until tick mark (a) is alignedwith the edge of the extension scale. Make a tick mark on the paper, in line with the 2,000-meter mark (c)(Figure 5-7A). Then slide the edge of the paper to the left until tick mark (b) is aligned with the zero.Estimate the 100-meter increments into 10-meter increments to determine how many meters tick mark (c)is from the zero line (Figure 5-7B). The total distance would be 3,030 meters.