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