Codes, Ciphers, and Cartography: Math Goes to War

Codes, Ciphers, and Cartography: Math Goes to War — page 5
The sextant gets its name because its In the 1750s the English mathematician curved scale covers John Bird invented the sextant This instrument about 60 degrees or measured the angle between any two objects one sixth of a circle In Latin sextans It helped sailors calculate latitude accurately means one sixth MARINE CHRONOMETER From the late fifteenth century the ships of Europe's navies explored the world Europeans set up new trade routes and colonies or overseas settlements Sailors needed a way to measure longitude For this they needed to know the exact time Most clocks and watches kept time poorly on sea voyages The problem was solved in 1735 The Englishman John Harrison built an accurate watch called a marine chronometer It compared the time on the ship with the time in London That helped sailors figure out their position by studying the position of the sun For the first time precise seafaring navigation possible was