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As you can imagine, 400 years ago,

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navigating the open ocean was difficult.[br]

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The winds and currents pushed and pulled ships off course,

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and so sailors based their directions on the port they left,

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attempting to maintain an accurate record of the ship's direction and the distance sailed.

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This process was known as dead reckoning,

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because being just half a degree off could result in sailing right past the island that lay several miles just over the horizon.

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This was an easy mistake to make.

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Thankfully, three inventions made modern navigation possible:

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sextants, clocks and the mathematics necessary to perform the required calculations quickly and easily.

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All are important. Without the right tools, many sailors would be reluctant to sail too far from the sight of land.

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John Bird, an instrument maker in London,

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made the first device that could measure the angle between the sun and the horizon during the day,

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called a sextant.

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Knowing this angle was important, because it could be compared to the angle back in England at the exact same time.

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Comparing these two angles was necessary to determine the longitude of the ship.

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Clocks came next.

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In 1761, John Harrison, an English clockmaker and carpenter,

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built a clock that could keep accurate time at sea.

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The timepiece that could maintain accurate time while on a pitching, yawing deck in harsh conditions

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was necessary in order to know the time back in England.

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There was one catch though:

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since such a timepiece was handmade, it was very expensive.

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So an alternate method using lunar measurements and intense calculations was often used to cut costs.

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The calculations to determine a ship's location for each measurement could take hours.

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But sextants and clocks weren't useful unless sailors could use these tools to determine their position.

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Fortunately, in the 1600s, an amateur mathematician had invented the missing piece.

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John Napier toiled for more than 20 years in his castle in Scotland to develop logarithms, a calculation device.

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Napier's ideas on logarithms involved the form of one over E and the constant 10 to the seventh power.

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Algebra in the early 1600s was not fully developed,

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and Napier's logarithm of one did not equal zero.

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This made the calculations much less convenient than logarithms with a base of 10.

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Henry Briggs, a famous mathematician at Gresham College in London,

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read Napier's work in 1614, and the following year made the long journey to Edinburgh to meet Napier.

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Briggs showed up unannounced at Napier's castle door

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and suggested that John switch the base and form of his logarithms into something much simpler.

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They both agreed that a base of 10 with the log of one equal to zero

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would greatly simplify everyday calculations.

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Today we remember these as Briggs Common Logarithms.

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Until the development of electric calculating machines in the 20th century,

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any calculations involving multiplication, division, powers, and extraction of roots with large and small numbers

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were done using logarithms.

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The history of logarithms isn't just a lesson in math.

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There were many players responsible for successful navigation.

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Instrument makers, astronomers, mathematicians,

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and of course sailors.

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Creativity isn't only about going deep into one's field of work,

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it's about cross-pollination between disciplines too.