way. Even though Harriot observed the Sun directly through his telescope, there were no recorded injuries to his eyes. Harriot's depiction of the sunspots were documented in 199 drawings that provided details about the solar rotation and its acceleration. Like many of Harriot's other notes, depictions of the sunspots were not published. Similar to the early observation of the Moon, Galileo was also known to contribute his observations of sunspots and published his findings in 1613. The specifics as to how Harriot's telescope was set up remains largely unknown. However, it is known that Harriot used different magnifications of telescopes with 10X and 20X power being used most often. Harriot chose to observe the sunspots after sunrise because it made the vertical easier to analyze. According to Harriot's notes there was a total of 690 observations of sunspots recorded. Harriot's findings challenged the idea of the unchanging heavens by explaining the Sun's axial rotation and provided further support for the heliocentric theory. Compounding Around 1620, Harriot's unpublished papers include the early basis of continuous compounding. Harriot uses modern mathematical concepts to explain the process behind continuous compounding. The concept of compounded interest occurs when the more times interest is added within the year assuming the rate stays the same then the final interest will be larger. Based on this observation, Harriot created mathematical equations that included logarithms and series calculations to illustrate his concepts. See also The School of Night References Sources External links Thomas Harriot: Trumpeter of Roanoke Thomas Harriot John Shirley papers related to Thomas Harriot, Special Collections, University of Delaware Library, Newark, Delaware. Works by Thomas Harriot A Brief and True Report online pdf text edition A Briefe and True Report of the New Found Land of Virginia from American Studies at the University of Virginia. Annotated Translation of Harriot's Praxis by Ian Bruce Works or sites about Thomas Harriot Harriot, Thomas The Englishman who beat Galileo The Soft Logic of Thomas Harriot The Thomas Harriot Seminar Searching for the Lost Colony Blog The Harriot Voyages of Discovery Lecture Series at East Carolina University The Thomas Harriot College of Arts and Sciences at East Carolina University, Greenville, NC Thomas Harriot Quintessential Renaissance Scholar Account of the Roanoke settlements Retrieved April 2011 1560s births 1621 deaths 16th-century astrologers 16th-century English mathematicians 17th-century astrologers 17th-century English mathematicians Algebraists Alumni of St Mary Hall, Oxford Atomists Creators of writing systems