Abstract
It is well known that Richard Hakluyt in a publication of 1581 congratulated Sir Walter Ralegh for employing Harriot to teach him and his many sea captains the sciences of navigation. Even more important, however, was the navigational research carried out by Harriot on behalf of Ralegh. He made important theoretical advances in map theory and in navigational astronomy, carried out the astronomical observations needed for a reform in navigational tables, and designed and himself tested at sea improved navigational instruments. Harriot had many other responsibilities in connexion with Ralegh's enterprises. From August 1585 to June 1586 Harriot was in Virginia, and in 1589 he was listed as one of Ralegh's colonists in Munster. He collected intelligence concerning America for Ralegh, and his publication of 1588 was effective as propaganda for Virginia. Harriot was also entrusted with financial, and even political responsibilities by Ralegh. Instructing Ralegh and his captains in navigation was an important part of Harriot's work but it is more likely that he did this as the occasion demanded, rather than on a regular basis.