The seventh son of an Ohio family, Edison had less than a year of formal schooling and was largely educated by his mother, a retired schoolteacher. For the rest of his life, he praised her for encouraging him to read as a child and to experiment on what intrigued him. For some years he worked as a telegraph operator but at the age of 30 became famous for his invention of the phonograph, a device that recorded sound on tinfoil, later wax cylinders, then vinyl; though the sound quality was poor, the mere fact of its existence in 1877 was held as amarvel and captured the public attention, helping to create the fascination the public would have with inventors and cutting-edge technology.