Harriot, Thomas (1560-1621), an English mathematician, was a pioneer in astronomy, navigation, optics, and mapmaking. Harriot is best known for his book on algebra, Artis analyticae praxis (1631). He was the first mathematician to use symbols to represent operations and concepts in his calculations. Mathematicians had previously noted such elements using Latin abbreviations. Harriot introduced symbols for greater than (>), less than (<), and square root (√). He also discovered Snell’s law, which describes the refraction (bending) of light by certain substances. Some historians believe that Harriot—and not the Italian scientist Galileo—may have been the first person to study the moon with a telescope.
Little is known about Harriot’s early life. Harriot was born in or near Oxford, England, in 1560. He graduated from Oxford University in 1580. Soon after, he began teaching mathematics and navigation to sailors under the leadership of the British explorer Sir Walter Raleigh in London. In 1585, Harriot sailed on Raleigh’s second expedition to the New World. During the expedition, Harriot wrote a report of the unexplored land of Virginia. The report in 1588 became the first book about the New World published in English.
In 1595, Harriot returned to England. He soon found employment with Henry Percy, the Earl of Northumberland. Percy provided Harriot with the means to conduct research in astronomy, optics, and mathematics.
Between 1609 and 1613, Harriot used an early telescope to observe and make drawings of the sun, the moon, and the satellites of Jupiter. Galileo is often credited with being the first person to use a telescope to study the moon. However, Harriot may have made observations and sketches of the moon a few months before Galileo. Harriot did not publish his studies. But he discussed his observations in letters to other astronomers, including Johannes Kepler of Germany. Harriot died of cancer in London on July 2, 1621.
