The discovery of schoolboy signatures - hidden under peeling wallpaper in an old Adelaide schoolhouse for 130 years - has led to this documentary history of John Lorenzo Young's school and its 1600 students, among them the leading lights of the colony and many still prominent in South Australian business and academic life today. John Lorenzo Young, the dissenting headmaster, was a brilliant and creative teacher, a graduate in the 'sciences of the enlightenment' from King's College London. He taught these new sciences to the sons of Adelaide's dissenting majority from 1852-1880, just 16 years after settlement. Adelaide's Dissenting Headmaster includes 230 biographies of Young's stellar and stalwart students, teachers and mentors, a school register, original photographs, and maps locating the six sites of the school in the city and at Parkside. Together they illuminate Adelaide's early character as it moved from fish oil to gas lamps to electricity, engineered and built by Young's schoolboys.