Short Talk

by Sashka Mannion

Space and Time in 17th century (Chapters 1-4 of Longitude by Dava Sobel)

September 23, 2003


If we were living in the 18th century we certainly would have known that the longitude problem was the hardest dilemma of the day and had been for centuries.

Background of the longitude problem: Lacking the ability to measure their longitude, sailors throughout the ages of exploration found themselves lost at sea as soon as they lost sight of land. In result, thousands of life and precious goods were lost.

The book Longitude summarized briefly: The book Longitude is a story of a scientific quest to accurately measure longitude at sea. The author (Dava Sobel) walks the reader throughout an English clockmakers 40-year straggle with building what is know today as chronometer (John Harrison). In their struggle to find longitude, the scientists of the 17th century made numerous important discoveries that changed the way people viewed the universe, and inventions about timekeeping that led to the make of the chronometer.

Body of Talk: Main points

Importance of longitude at sea: Unable to measure longitude while at sea every great captain in the Age of exploration became lost at sea [] from Vasko da Gama to Vasco Nunez de Balboa, from Magellan to Sir Francis Drake (L, 6).

Lost at sea = lost of lives and economic havoc


In October 22, 1707, incorrectly measured longitude caused the lives of 2 000 sailors on the ship of Sir Clowdsley.

No good system known for preserving fresh fruits and vegetables or meat. So, extra day at sea, more lives lost.

The pirates. Merchant ships tried to stick to well established shipping lines, which made them an easy target for the pirates. The ship Madre de Deus for example, was carrying gold and silver coins, pearls, diamonds, amber, musk, tapestries, calico, and ebony; more than 400 tons of pepper, 45 tons of cloves, 35 tons of cinnamon, and three tons each of mace and nutmeg (L, 15).

Solving the longitude problem became a necessity: Almost for two centuries, the greatest of the scientific minds were occupied in finding solution for the longitude problem, when in 1714, the English parliament offered 20 000 pounds (the equivalence of $12 000 000 todays currency) to anyone whose method or device proved successful.

Two possible ways for solving the longitude problem were suggested:

An accurate clock (showing the time at land of departure)

The use of the moon and stars (precise position of astronomical object could assist in determining the time at land of departure)

The problems: Such accurate clock did not exist, nor did precise chats of the sky.

Drawing charts of the sky seemed easier task to accomplished, scientists turned their attention to the heavens:

Accomplishments in astronomy:

Observatories were built.

Stars and planets were carefully observed to document their movement.

First detailed charts of the sky were drawn.

Many anomalies were noticed, and in order to proceed further with straggles to predict the exact position of a certain star of plane, scientists had to find out the reason for these anomalies.

So they discovered:
The speed of light was measured almost accurately (slightly under 300 000 km/ hr).
Theories for the behavior of light were developed.
Gravitational forces were recognized.

The idea of precise clock renewed:

In the 17th century, the idea of developing an accurate clock was renewed, and numerous inventions were made:

In 1937 Galileo invented the pendulum clock
Independently, Huygens invented the pendulum clock
In 1675 Huygens invented the spiral balance springe to the pendulum
In 1773 after 40years of straggle the chronometer was introduced.


While we cannot say that without the existence of the longitude dilemma all of these inventions and discoveries would not have been made, we can most definitely conclude that it did speed up the process. And since we a talking about events that occurred only 300 year ago, the longitude dilemma played a major role in the history of astronomy, navigation, and timekeeping.

Contact Ellen Moody.
Pagemaster: Jim Moody.
Page Last Updated: 7 January 2007.