michelle mendez caitlin roberts. john dee- “the art of navigation demonstrates how, by the...
TRANSCRIPT
Michelle Mendez
Caitlin Roberts
History of Navigation, Geography, and the Longitude
Problem
John Dee- “The art of Navigation demonstrates how, by the shortest good way, by the aptest direction, and in the shortest time, a sufficient ship between any two places assigned, may be conducted, and in all storms and natural disturbances chancing, how to use the best possible means, whereby to recover the place first assigned.”
Navigation
The country that could come up with the newest techniques were better offNew coloniesNatural resources
Advantages
Pedro Nunez (1537) Loxodromes or latitudes were straightMeridians or Longitudes converged (spiral
terminating at pole)Gerard Mercater
Mercater’s projectionParallel’s and meridians represented by
straight lines (compensated by increased spacing at poles)
Mapmaking
Because parallels and meridians were straight navigators could use straight edge on a map between origin and destination to determine compass bearing.
No mathematical justification
Mapmaking
1599Ratio of length of a degree of longitude at
latitude Ø to one at the equator is equal to cosØ
Degree of longitude @ Latitude Ø = cosØ
Degree of longitude @ Latitude equator(if meridians are straight)Distances between meridians @ Lat. Ø stretch
by factor of Sec Ø
Wright’s Justification
Could navigator’s apply maps to actually being out in the sea????
How can a ship determine how far East or West it is from its origin??
For every 15° one travels Eastward, local time moves one hour ahead. Similarly, 15° Westward moves one hour back
If we know local times in 2 places at one given time, we can tell how far apart they are
Navigator’s could measure time by sun, but required time at reference point
http://www.youtube.com/watch?v=y6w5Q7tRX88&feature=related
The Longitude Problem
Columbus attempted Longitude 1494 using Eclipse
1675 King Charles II founded Royal Observatory to find solution
Needed a way to tell time in two different locations at same time
Longitude attempts
If accurate catalog of position of stars made and measure accurately the position of the Moon, then Moon’s motion could be natural time keeper to calc. Greenwich time
Sailors used combination of measure of position of moon relative to stars and tables of moon’s positions in Royal Observatory to get time at Greenwich.
Lunar Distance Method
1707, four British war ships ran aground.1714 British Gov. offered £ 20,000
($12,000,000) for method to determine longitude
Last chance
John Harrison- very little formal educationClockmaker1730-1735 portable version of Harrison’s
wooden clock (H1)Tested trip on Centurion and OrfordKept time accurately only lasts for 1 dayAsked Board of Longitude for money
Harrison
H2- 1737Heavier than H11740- realized wrong design and bar balances
did not always counter motion of ship
H3Bimetallic strip to compensate the balance
spring for effects of changes in temp.Caged roller bearing- ultimate version of
antifriction
H2 and H3
1755Hired John Jeffreys to help make a pocket watch
for personal use for astronomical testing13 cm in diameter and 1.45 kgTrial 1• Harrison’s son sailed to W. Indies on Deptford
estimated time was only 5.1 sec. offTrial 2
Barbados to Madeira error 39.2 over 47 daysThree times better than time required to win prize
H4
Board of Longitude wouldn’t accept H4 was legitimate
Required that Harrison make two more copies himself and have someone else create their own model of H4 to prove not a fluke
Original H1-H4 sent to Royal Observatory to be studied and tested
Appointed Larcum Kendall to make his own construction
Rejection
Harrison made H5 while Kendall made copy of H4 also called K1 1769
Asked board since both models worked, could be the two extra models of H4
Appealed to King George III at 79Private Interview with King
“…These people have been cruelly wrong…By God Harrison, I will see you righted!!”
H5 and K1
H5 trialed by KingBoard refused to recognize resultsPetitioned parliament 1773 recognized as solving longitude problem
Bittersweet Justice