contemporary lullabies. However, most of those used today date from the seventeenth century onwards. Some rhymes are medieval or sixteenth-century in origin, including "To market, to market" and "Cock a doodle doo", but most were not written down until the eighteenth century, when the publishing of children's books began to move towards entertainment. The first English collections were Tommy Thumb's Song Book and a sequel, Tommy Thumb's Pretty Song Book, both thought to have been published before 1744, and at this point such songs were known as "Tommy Thumb's songs". The publication of John Newbery's Mother Goose's Melody; or, Sonnets for the Cradle (c. 1785) is the first record we have of many classic rhymes still in use today. These rhymes seem to have come from a variety of sources, including traditional riddles, proverbs, ballads, lines of mummers' plays, drinking songs, historical events, and, it has been suggested, ancient pagan rituals. Roughly half of the current body of recognised "traditional" English rhymes were known by the mid-eighteenth century. In the early nineteenth century, printed collections of rhymes began to spread to other countries, including Robert Chambers's Popular Rhymes of Scotland (1826) and, in the United States, Mother Goose's Melodies (1833). We sometimes know the origins and authors of rhymes from this period, such as "Twinkle Twinkle Little Star", which combined an eighteenth-century French tune with a poem by the English writer Jane Taylor, and "Mary Had a Little Lamb", written by Sarah Josepha Hale of Boston in 1830. Nursery rhymes were also often collected by early folk-song collectors, including, in Scotland, Sir Walter Scott and, in Germany, Clemens Brentano and Achim von Arnim in Des Knaben Wunderhorn (1806–08). The first, and possibly the most important, academic collections to focus in this area were James Orchard Halliwell's The Nursery Rhymes of England (1842) and Popular Rhymes and Tales (1849). By the time of Sabine Baring-Gould's A Book of Nursery Songs (1895), child folklore had become an academic study, full of comments and footnotes. The early years of the twentieth century are notable for the addition of sophisticated illustrations to books of children's songs, including Caldecott's Hey Diddle Diddle Picture Book (1909) and Arthur Rackham's Mother Goose (1913). The definitive study of English rhymes remains the work of Iona and Peter Opie. Children's playground and street songs In contrast to nursery rhymes, which are learned in childhood and passed from adults to