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History of Oceanography II

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1 History of Oceanography II
September 2008 Text Website:

2 Navigational Tools Latitude/Longitude Astrolabe, Sextant, and Chip Log
Latin root “navis” and “agere” “to move or direct” Latitude/Longitude Chronometer Astrolabe, Sextant, and Chip Log Charts/Maps Compasses Echo Sounders Satellites

3 Finding Latitude at Sea
Used the altitude of the North star and the angle of the ship The angle of degrees what the latitude of the ship Celestial Navigation


5 Finding Longitude Chronometer (1773)
Time piece that wasn’t affected by gravity Invented by John Harrison Used the difference in time of day from start to current position Normal Pendulum clocks lost 10 minutes per day Off course by 150 miles or more (242 km) James Cook used Chronometer to circumnavigate the globe (1779) New Charts of the World 1884 Prime Meridian made 0° Longitude through Greenwich, England 15° = 1 hour

6 Most of the wheels are made of wood
                                Harrison's H1 (built ). Height 76 cm Weight 36 kg Most of the wheels are made of wood Accurate to within a couple of seconds per day The longitude is directly related to the difference between true local time and Greenwich time: 1 hour time difference = 15 degrees longitude difference

7                                 Harrison's Watch H4 Completed in 1759 On two trials across the Atlantic, it determined the longitude within 10 nautical miles

8 H1 H3 H4 Harrison’s Chronometers

9 Mariner’s Compass Early form of the magnetic compass
Formed 32 points Mariners thought that compass was wrong Didn’t understand magnetic variation of compass at the time Angle between magnetic north and true north Used to determine where wind was coming from when sun was down Early Chinese first to use compass ~1040 AD Loadstone/Magnetite

10 Diagram of a Ming dynasty mariner's compass


12 Nautical Maps/Charts ~ 13th Century Emergence of Maps and Charts of open water Ptolemy’s map 127 AD Polynesian Stick Maps

13 Ptolemy's World Map - 150AD

14 Charting Currents 1777 Benjamin Franklin 1806 Matthew Maury
Gulf Stream Map 1806 Matthew Maury Father of Modern Oceanography US Navy Cataloged wind and currents of ocean 1855 Wrote: The Physical Geography of the Sea


16 Astrolabe, Sextant, and Chip Log
Dates back to Greece Helped to tell time ~ 15 Century Used to determine latitude Altitude of the stars was taken Angle

17 Astrolabe in use.For a sun sight, the astrolabe was allowed to hang freely and the alidade was adjusted so that a ray of sunlight passed through the hole in the upper vane and fell precisely on the hole in the lower vane.                                                                                                                                      

18 Sextant/Quadrant 1730 Independently Invented
John Hadley (English) Thomas Godfrey (American) More accurately measured the angle of horizon and stars More accurate latitude


20 Chip Log Speedometer Line containing knots at intervals
Counted knots over time


22 Gyroscopic Compass 1907 to present Points always to True North
Not affected by metal on hull of ship Uses electricity power

23 Soundings Before soundings, ocean floor thought to be featureless
Used hand lines with weights to find depth and features of ocean floor Challenger expedition Canon ball with piano wire Made determining touch easier 1895, only 7000 soundings of deep ocean had been made (2000 m or greater)

24 Echo Sounders ~ 1914 World War I Determines Ocean floor Depth
Uses Reflection of Sound waves Primitive sonar 1925 German ship Meteor Charted ocean depth and discovered the mid-Atlantic ridge 1950’s first detailed chart of ocean floor



27 Satellites 1978 NASA launches Seasat
Sea-surface temperature Surface wind speed and direction Directional wave spectra Satellite included Radar altimeter Wind field scatterometer Microwave radiometer Radiometer operating in visual and infrared 1992 US/France Launch TOPEX/Poseidon Ocean circulations interaction with the atmosphere


29 Radar Altimeter

30 Microwave Radiometer

31 The Future Private/institutional and national oceanographic institutions Observing process that take place Looking at ocean basins with observatories Using ROV and AUV Science of the Deep


33 GPS: Global Positioning System
Global Navigation Satellite System (GNSS) Uses 28 earth orbiting satellites, 11,000 mi above Earth, 12 hour orbit around Earth Location Speed/Direction Time



36 Citations 1557 sailors using instruments of navigation.. IRC unitedstreaming. 17 September 2008 <

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