michelle mendez caitlin roberts. john dee- “the art of navigation demonstrates how, by the...

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