| A | B |
|---|
| Aqua | A NASA satellite designed to obtain data on Earth’s water cycle. |
| Challenger expedition | The first wholly scientific oceanographic expedition, 1872–76; named for the steam corvette used in the voyage. |
| Maury, Matthew | “Father” of physical oceanography. Probably the first person to undertake the systematic study of the ocean as a full-time occupation. |
| Meteor expedition | German Atlantic expedition begun in 1925; the first to use an echo sounder and other modern optical and electronic instrumentation. |
| latitude | Regularly spaced imaginary lines on Earth’s surface running parallel to the equator. |
| bathyscaphe | Deep-diving submersible designed like a blimp, which uses gasoline for buoyancy and can reach the bottom of the deepest ocean trenches. |
| cartographer | A person who makes maps and charts. |
| celestial navigation | The technique of finding one’s position on Earth by reference to the apparent positions of stars, planets, the moon, and the sun. |
| Nautical chart | A chart used for marine navigation. |
| chronometer | A very consistent clock. It doesn’t need to tell accurate time. |
| Columbus, Christopher | Italian explorer in the service of Spain who discovered islands in the Caribbean in 1492. |
| compass | An instrument for showing direction by means of a magnetic needle swinging freely on a pivot and pointing to magnetic north. |
| Cook, James | Officer in the British Royal Navy who led the first European voyages of scientific discovery. |
| Darwin, Charles | An English biologist and the co-discoverer (with Alfred Russell Wallace) of evolution by natural selection. |
| echo sounder | A device that reflects sound off the ocean bottom to sense water depth. Its accuracy is affected by the variability of the speed of sound through water. |
| Eratosthenes of Cyrene | Greek scholar and librarian at Alexandria who first calculated the circumference of Earth about 230 b.c. |
| Ben Franklin | Published the first chart of an ocean current. |
| Global Positioning System | Satellite-based navigation system that provides a geographical position. |
| longitude | Regularly spaced imaginary lines on Earth’s surface running north and south and converging at the poles. |
| Magellan, Ferdinand | Portuguese navigator in the service of Spain who led the first expedition to circumnavigate Earth, 1519–22. |
| Sounding | Measurement of the depth of a body of water. |
| Tropic of Cancer | The imaginary line around Earth parallel to the equator at 23°27’N. |
| Tropic of Capricorn | The imaginary line around Earth parallel to the equator at 23°27’S. |
| vikings | Seafaring Scandinavian raiders who ravaged the coasts of Europe around a.d. 780–1070. |
