Roman Mars

And you can get even more precise than that.

One hour equals 15 degrees of longitude.

This might sound like a pretty simple solution to the problem of longitude at sea.

Just set a clock before leaving and take it on board your ship.

During this era, all clocks were kind of crappy.

But bring one of those crappy clocks on board a ship and it was useless.

These were mostly pendulum clocks.

And you can imagine how well a pendulum clock would work on a rocking ship.

But where others saw problems, John Harrison saw an opportunity.

He thought he could solve longitude not by looking at the stars, but by building a better clock.

He also solved the problem of temperature by combining complementary metals, steel and brass, that expand at different rates and at different temperatures, which stopped the metal components from changing shape.

To deal with the problem of keeping a pendulum clock running on a rocking ship, Harrison made a modified pendulum with two connected bar balances that compensate for each other's motion.

A clock with these balances could keep time even when tilted around.

After Harrison finished H1 in 1735, he got in front of England's premier research institute, the Royal Society.

This was a big moment for Harrison.

A good review from the society might put his invention in front of the judges of the Longitude Act.

Harrison apparently got extremely seasick on the trip.

Like seasick enough that we are still talking about it 290 years later.

But H1 performed marvelously.

Harrison's timekeeper was able to correct the ship's longitude.