maps peterson. ptolemy 1100 ad mercator 1500s
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Maps
Peterson
Ptolemy
1100 AD
Mercator
1500s
Sextant to determine latitude
John HarrisonLate 1700s
360° / 24 hours in a day = 15°
Earth rotates 15° every hour
Keep chronometer on GMT (0°)
Compare current sunrise / sunset to tables of sunrise/sunset at Greenwich.
If sunrise at 8 AM.Sunrise at Greenwich at 6 AMLongitude = 30° W
Mollweide Equal-area
12 inches in a foot5280 feet in a mile63,360 inches in a mile
RF 1:24,000How many miles to an inch?
24000/63000 = 0.3781 in : 0.378 miles
RF 1:100,000How many inches in a mile ?
100,000 / 63,360 = 1.57821 in: 1.5782 miles
100 cm in a meter1000 meters in a KM100,000 cm in a KM
RF 1:24,000How many KM to a cm?
24000/100,000 = 0.241 in : 0.24 KM
RF 1:100,000How many KM to a cm?
100,000 / 100,00 = 1.01 cm: 1 KM
GIS
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