Chapiter 1
This ancient Greek cartographer and astronomer plotted latitude and longitude on the 27 maps of his world atlas by A.D. 150.
Who is Ptolemy?
This navigational error—central to the disaster—led the admiral to execute a sailor whose independent calculations later proved correct.
What is a miscalculation of longitude?
This Italian astronomer proposed using the predictable eclipses of Jupiter’s moons as a “clock of heaven” to determine longitude at sea.
Who was Galileo Galilei?
Early watches were unable to solve the longitude problem mainly because they couldn’t do this reliably on long sea voyages.
What is keep accurate time?
This unit of time corresponds to fifteen degrees of longitude because the Earth rotates 360 degrees in twenty-four hours.
What is one hour?
This zero-degree line of latitude was fixed by nature and named by Ptolemy based on astronomical observations.
What is the Equator?
This British admiral lost four warships and nearly two thousand men after misjudging his fleet’s position in a fog in 1707.
Who was Admiral Sir Clowdisley Shovell?
This French king reportedly complained that accurate longitude measurements were costing him more territory than his enemies when new maps redrew his realm.
Who was King Louis XIV?
This Dutch scientist built the first working pendulum clock in 1656 and later invented the spiral balance spring after pendulums failed at sea.
Who was Christiaan Huygens?
To determine longitude at sea, a navigator must compare local noon on the ship with this reference time from a known location.
What is home port's time?
(Or, What is a clock set to a known longitude?)
Unlike the equator, this geographic reference line can be placed anywhere and has shifted locations for political reasons throughout history.
What is the prime meridian?
These islands near Land’s End became fatal “tombstones” when the English fleet wrecked upon them on October 22, 1707.
What are the Scilly Isles?
This Italian-born astronomer published highly accurate ephemerides in 1668 and later became director of the Paris Observatory under Louis XIV.
Who was Giovanni Domenico Cassini?
This Flemish astronomer suggested in the 1500s that accurate clocks could help sailors figure out longitude at sea.
Who was Gemma Frisius?
This deadly disease, caused by a lack of vitamin C during long sea voyages, led to bleeding gums, failing wounds, and often death among sailors.
What is scurvy?
These two famous parallels mark the northern and southern limits of the sun’s apparent movement during the year.
What are the Tropic of Cancer and the Tropic of Capricorn?
This 1714 act of Parliament offered a £20,000 prize for solving the problem made urgent by shipwrecks like the 1707 Scilly disaster.
What is the Longitude Act?
This astronomical institution, founded in 1666 with the support of Louis XIV and Jean-Baptiste Colbert, helped advance efforts to solve the longitude problem.
What is the French Académie Royale des Sciences?
This multitasking English scientist disputed Christiaan Huygens’s claim to inventing the spiral balance spring, sparking a bitter priority fight within the Royal Society.
Who was Robert Hooke?
This 16th‑century German astronomer proposed using the moon’s movement against the stars as a celestial clock to determine longitude.
Who was Johannes Werner?
This was Ptolemy’s chosen location for the prime meridian, now known as the Canary Islands.
What are the Fortunate Islands?
This 1592 capture of a Portuguese galleon yielded spices, jewels, and treasure worth about half the value of the entire English Exchequer.
What was the Madre de Deus?
By noticing that the eclipses of Jupiter’s moons ran early when Earth was closer to the planet and late when it was farther away, this astronomer used interplanetary distances in 1676 to make the first successful measurement of a quantity once thought instantaneous (can we guess what this quality is for double points?).
Who was Ole Rømer?
This invention replaced the pendulum in clocks to reduce the effects of a ship’s motion and was patented in France in 1675.
What is the spiral balance spring?
This telescope-equipped navigation helmet, designed by Galileo to observe Jupiter and its moons, resembled a brass gas mask.
What is the celatone?