All forms of English literature were now in print, except for plays. In 1600 William Gelbert wrote a book on terrestrial magnetism which founded the science of electricity. He cultivated the method of experiment and of inductive reasoning from observation. He expounded the idea of Nicolaus Copernicus of Poland published in 1543 that the earth revolves around the sun in a solar system. However, the prevailing belief was still that the earth was at the center of the universe. Many people kept diaries. Letter-writing was frequent at court. Correctness of spelling was beginning to be developed. Printers tended to standardize it. There was much reading of romances, jest books, histories, plays, prayer collections, and encyclopedias, as well as the Bible. In schools and gentry households, favorite reading was Edmund Spenser's "Faerie Queen" about moral virtues and the faults and errors which beset them, Erasmus' New Testament, "Paraphrases", "Colloquies", and "Adages", Sir Thomas North's edition of Plutarch's "Lives of the Noble Grecians and Romans", Elyot's "The Book Named the Governor", and Hoby's translation of "The Courtier". At a more popular level were Caxton's "The Golden Legend", Baldwin's "Mirror for Magistrates", Foxe's "Book of Martyrs" about English protestant who suffered at the stake, sensational stories and pamphlets, printed sermons (including those of Switzerland's Calvin), chronicles, travel books, almanacs, herbals, and medical works. English fiction began and was read. There were some books for children. Books were copywrited, although non-gentlemen writers needed a patron. At the lowest level of literacy were ballads describing recent events. Next to sermons, the printing press was kept busiest with rhymed ballads about current events. Printed broadsheets on political issues could be distributed quickly. In London, news was brought to the Governor of the News Staple, who classified it as authentic, aprocryphal, barber's news, tailor's news, etc. and stamped it. Books were also censored for matter against the state church. This was carried out through the Stationers' Company. This company was now, by charter, the official authority over the entire book trade, with almost sole rights of printing (e.g. excluding schools). It could burn other books and imprison their printers. Travel books had maps, itineraries, and mileage between towns in England and Wales according to a survey completed in 1579, about which time the Queen had a postal system on the high roads for official business. Non-government people used private post horses. The gentry rode horses. Most people's mode of travel was still walking. In 1564, the first canal was built with locks at Exeter.