The navigation over the Atlantic ocean was for Charles Lindbergh not as simple as it is our days.He had to solve a few problems in order to maintain his course. First he had to compensate the effect of the wind over his aircraft.
Second, he had to consider the magnetic declination (the magnetic north do not coincide with the real north). For this he used the dead reckoning method. He had to estimate his current position based upon a previously determined position, or fix, and advanced to that position based upon known or estimated speeds over elapsed time.
To make it simple Lindbergh used an Earth Inductor Compass (EIC) to avoid complex calculations. The EIC was invented in 1924 by Morris Titterington at the Pioneer Instrument Company.
This instrument use the Earth's magnetic field as the induction field for an electric generator. Because the direction of the Earth's magnetic field is aligned nearly north-south, the electrical output of the generator will vary depending on its orientation with respect to the Earth's magnetic field. This variation in the generated voltage is measured, allowing the Earth inductor compass to determine direction.
At some times Lindbergh used also the stars to for orientation during his long flight.
Today there are other instruments such as GPS, able provide reliable navigation capability under virtually any conditions, with or without external references.
1.Locate the cities of New York in the United States and Paris, France in Europe on a large wall map of the world. Observe the locations (latitude and longitude) of these cities.
2. Draw the shortest route between New York and Paris on a flat map. Locate the island of Newfoundland in Canada and ask why did Lindbergh flew over it instead following the straight line on the map. Draw the real flight route on the globe and compare the lengths with the your initial drawing on the flat map. Observe that New York, Newfoudland and Paris are all on a big circle over the globe.
3.Divide the flight route in equal segments and glide the compass along the route. Note it’s readings at different points.