Michelle Mendez
Caitlin Roberts
 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.”
 The country that could come up with the newest
techniques were better off
 New colonies
 Natural resources
 Pedro Nunez (1537)
Loxodromes or latitudes were straight
 Meridians or Longitudes converged (spiral terminating
at pole)

 Gerard Mercater
 Mercater’s projection
 Parallel’s and meridians represented by straight lines
(compensated by increased spacing at poles)
 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
 1599
 Ratio 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
 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&fea
ture=related
 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
 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.
 1707, four British war ships ran aground.
 1714 British Gov. offered £ 20,000 ($12,000,000) for
method to determine longitude
 John Harrison- very little formal education
 Clockmaker
 1730-1735 portable version of Harrison’s wooden clock
(H1)
 Tested trip on Centurion and Orford
 Kept time accurately only lasts for 1 day
 Asked Board of Longitude for money
 H2- 1737
 Heavier than H1
 1740- realized wrong design and bar balances did not
always counter motion of ship
 H3
 Bimetallic strip to compensate the balance spring for
effects of changes in temp.
 Caged roller bearing- ultimate version of antifriction
 1755
 Hired John Jeffreys to help make a pocket watch for
personal use for astronomical testing
 13 cm in diameter and 1.45 kg
 Trial 1
• Harrison’s son sailed to W. Indies on Deptford estimated
time was only 5.1 sec. off
 Trial 2
 Barbados to Madeira error 39.2 over 47 days
 Three times better than time required to win prize
 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
 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 79
 Private Interview with King
“…These people have been cruelly wrong…By God
Harrison, I will see you righted!!”
 H5 trialed by King
 Board refused to recognize results
 Petitioned parliament
 1773 recognized as solving longitude problem