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Extra info for Aerial Navigation [Pt. I, II] (the compass and the map)- Div. Mil. Aeronautics, US Army

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F. of 1/100,000? (5) Two points are 6 inches apart on a map whose R. F. is 1/40,000. Give the distance on the ground in miles. Give its R. F. (6) (a) The scale of a map is 3 inches to the mile. (6) To what French map does it correspond? (7) The distance between two trees is measured and found to be 500 yards; on the map they show to be 2 inches apart. What is the R. F. of the map? 7 inches apart on a map whose R. F. is 1/100,000, find the distance in miles (kilometers). 7 inches (9) The scale of the map is 1/20,000.

R The p rman^nt swinging base, such as is us d at factcri s, schools, and p rman^nt aerodrome s, is made by digging a circular basin 20 yards in diamet r and about 1 foot deep, and filling it with cono\ te. When leveled and s t, the platform thus formed is marked off with the cardinal and quadrantal points as above, the lin:s being marked with black paint inst ad of cords and p gs. Before the machine and coir pass are taken to the swinging base for the adjustment, the coir pass must be car fully inep ct d for its mechanical condition.

8) It is 11. customary to break contours when crossing roads, them on the other side. , continuing FIG. 12. Examples. The following examples are given to illustrate the principles of conventional signs and contours: (1) Illustrate by means of 10-foot contours: (a) A hill of 75 feet elevation, rising for the first 30 feet gradually and being very steep for the last 45 feet; (b) a hill of the same elevation rising steeply for the first 30 feet, gently the last 45 feet; indicate a stream on the last hill.