subjects if they made no trouble. In 1570, Pope Pius V declared Elizabeth a heretic who was not the legitimate queen and that her subjects no longer owed her obedience. The pope sent Jesuits and seminarians to secretly evangelize and support Catholics. After several plots to overthrow her, Catholic clergy were mostly considered to be traitors, and were pursued aggressively in England. Often priests were tortured or executed after capture unless they cooperated with the English authorities. People who publicly supported Catholicism were excluded from the professions; sometimes fined or imprisoned. This was justified on the grounds that Catholics were not persecuted for their religion but punished for being traitors who supported the Queen's Spanish foe; in practice, however, Catholics perceived it as religious persecution and regarded those executed as martyrs. Science, technology, and exploration Lacking a dominant genius or a formal structure for research (the following century had both Sir Isaac Newton and the Royal Society), the Elizabethan era nonetheless saw significant scientific progress. The astronomers Thomas Digges and Thomas Harriot made important contributions; William Gilbert published his seminal study of magnetism, De Magnete, in 1600. Substantial advancements were made in the fields of cartography and surveying. The eccentric but influential John Dee also merits mention. Much of this scientific and technological progress related to the practical skill of navigation. English achievements in exploration were noteworthy in the Elizabethan era. Sir Francis Drake circumnavigated the globe between 1577 and 1581, and Martin Frobisher explored the Arctic. The first attempt at English settlement of the eastern seaboard of North America occurred in this era—the abortive colony at Roanoke Island in 1587. While Elizabethan England is not thought of as an age of technological innovation, some progress did occur. In 1564 Guilliam Boonen came from the Netherlands to be Queen Elizabeth's first coach-builder —thus introducing the new European invention of the spring-suspension coach to England, as a replacement for the litters and carts of an earlier transportation mode. Coaches quickly became as fashionable as sports cars in a later century; social critics, especially Puritan commentators, noted the "diverse great ladies" who rode "up and down the countryside" in their new coaches. Social history Historians since the 1960s have explored many facets of the social history, covering every class of the population. Health Although home to only a small part of the population the Tudor municipalities were overcrowded and unhygienic. Most towns