The Story of The Story of LongitudeLongitude

The Greatest Intellectual The Greatest Intellectual Puzzle of the 16Puzzle of the 16thth and 17 and 17thth

CenturiesCenturies

What Are We Doing?What Are We Doing?

Content Area Study

Cross Discipline Unit

Social Studies is Everything!

Using Technology for Differentiation

First, a Story

Latitude & LongitudeLatitude & Longitude

Latitude is Easy to FindLatitude is Easy to Find

The angle of the sun over the horizon on any given day is directly related to the location one is viewing from.

Determining LatitudeDetermining Latitude

Was Chris Really Taking a Was Chris Really Taking a Chance?Chance?

Columbus would have used a magnetic compass, a speed log, and a logbook.

He was what we now call a dead reckoning navigator.

Because he could NOT determine longitude,his course would have looked like this:

We Understand Latitude -

But What About Longitude?

Longitude is a Longitude is a Measurement of TIME Measurement of TIME translated to DEGREEStranslated to DEGREES

Longitude - measuredLongitude - measuredin minutes, secondsin minutes, seconds

1 degree=60 minutes=1 degree=60 minutes=69 miles69 miles

1 second=1.15 miles (eq)1 second=1.15 miles (eq)

So, put it togetherSo, put it together

Location is Now a GridLocation is Now a Grid

Expressed in degrees N or S of the equator – Latitude &

degrees E or W of Greenwich (Prime Meridian)-Longitude

But the Devil is in the But the Devil is in the DetailsDetails

• In 1700, there was no accurate way to In 1700, there was no accurate way to measure time.measure time.

• In order to be practical, time In order to be practical, time measurement must be accurate to measurement must be accurate to within a few seconds every month.within a few seconds every month.

• A time keeping device must function A time keeping device must function perfectly on a sailing ship at sea – in perfectly on a sailing ship at sea – in the most corrosive atmosphere the most corrosive atmosphere possible.possible.

Enter John Harrison, clockmakerEnter John Harrison, clockmaker

Harrison’s Successful Chronometer – H4

Time at the Prime Meridian

Less local time

measured at Noon =

Longitude

Now, English Ships Could Travel Diagonally

H4 – A Technological H4 – A Technological AdvancementAdvancement

Led to….Led to….

• Superior English NavigationSuperior English Navigation

• English Mastery of the SeasEnglish Mastery of the Seas

• Establishment of a World Wide Establishment of a World Wide EmpireEmpire

• Fundamental Shift in the World’s Fundamental Shift in the World’s Power Power

• Alteration of World History…..andAlteration of World History…..and

• Made our World Made our World