Metal Detecting Research and Exploration - A Complete Guide, page 26
Formulas for Basic Calculations Used in Map Analysis
1. CONVERTING BETWEEN SCALE TYPES OF HISTORIC AND MODERN MAPS
I included simple formulas and their descriptions into the pages listed below, which will help you convert scale types in a fast and error-free way, and without figuring out the "algorithms" of conversions.
To correctly convert between different types of map scales, make sure you use appropriate units in formulas. Otherwise, the units will not cancel properly during calculation. Listed below are three common situations that occur during map research.
1) Converting Bar Scale to Representative Fraction (RF)/Ratio Scales
2) Converting Representative Fraction (RF)/Ratio Scales to Lexical Scale
3) Converting Lexical Scale to Representative Fraction (RF)/Ratio Scales
English and Metric Measures of Length to use:
1 inch (in) = 2.54 centimeters
1 centimeter (cm) = 0.39 inch
1 foot (ft) = 12 inches = 30.5 centimeters = 0.3 meter
1 yard (yd) = 36 inches = 3 feet = 91.44 centimeters = 0.9 meter
1 meter (m) = 100 centimeters = 39.37 inches = 3.28 feet = 1.09 yards
1 mile (mi) = 63,360 inches = 5,280 feet = 1,760 yards = 1.609 kilometers
1 nautical mile = 1,852 meters = 1.852 kilometers
1 kilometer (km) = 1,000 m = 100,000 cm = 1,094 yards = 0.6 mile
NOTE: When you carry out any calculation with fractions, make sure that all units in equation are cancelled correctly. If necessary, invert the RF for that purpose.
2. CALCULATING GROUND DISTANCE AND AREA FROM MAP WITH SCALE
To help you determine distances in a fast and error-free way, and without figuring out the "algorithms" of calculations, I included simple formulas and their descriptions into the pages listed below.
To correctly calculate ground distances between objects shown on various maps, make sure you use appropriate units in equations. Otherwise, the units will not cancel properly during calculation. Listed below are three common situations that occur during map research.
1) Calculating Ground Distance from Map with RF/Ratio Scale
2) Calculating Ground Distance from Map with Lexical Scale