A scientific writer of the Enlightenment, and an Anglican priest, Harris published an early English encyclopedia, the famous Lexicon technicum, or, An Universal English Dictionary of Arts and Sciences (1704 and 1710). It was one of the first books to bring to public notice Newton’s scientific theories. He had a special interest in the “scientific instruments, such as the air-pump, that provided the Royal Society with many experiments, as well as in the technology of the Savery engine and in the practical problems of navigation” (Larry Stewart).
In cartographic circles, Harris is best known for his Navigantium atque itinerantium bibliotheca, or, A compleat collection of voyages and travels, consisting of above four hundred of the most authentick writers, which he began to compile in 1705, revised in 1744, and which included a number of important maps, and popularized many voyages of exploration and discovery.
Harris served briefly as secretary of the Royal Society (1709–10), and at his death was compiling a voluminous history of the county of Kent.