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Math

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Math is the underlying knowledge needed to make use of the angles and distances measured with other navigational instruments. Advancements in mathematics from the Ancient Greeks to the modern day have shaped our understanding of both navigation and the universe as a whole; the importance of mathematics in predictive efforts writ large is expanded upon in greater detail in the Path to Newton.

In Lost Without Longitude, we present only one example of a tool used for calculating mathematics -- Galileo's compass.

Galileo's Compass

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Description: Galieo's Geometic and Military Compass is a device that was, in some ways, a precursor to the slide rules used in by 20th century engineers. While other individuals such as Fabrizio Mordente and Thomas Hood created similar devices (all called "Sectors"), Galileo's is the best known, perhaps because of his fame in other areas.

Sectors were used by military officers and engineers for a variety of purposes: to measure distances and angles, to make a wide range of mathematical calculations, and even to determine how much gunpowder should be used for a cannonball of a particular type.

Related Instruments: SectorSlide Rule

Usage Dates: Late 1500s to late 1800s

Images:

Compass Diagram

Compass Diagram

A diagram of a similar device, from Galileo's own book on the device.

Galileo's Compass

Galileo's Compass

A photo of Galileo's personal compass, taken at the Harvard Museum of Historical Scientific Instruments.

Compass Crossbar

Compass Crossbar

Close-up on the crossbar of the same compass. Angle and length markings can be seen on every surface.

Compass "Arm"

Compass "Arm"

Close-up on the end of one "arm" of the same compass. Marks for measurement and calculation can be seen.

Similar Sector

Similar Sector

A sector similar to Galileo's compass, seen in an exhibit in Dresden, Germany.

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