"Founded Upon The Mysteries Of Electricity And The Optimism Of Its Devotees. It Was Written For Boys, But Others May Read It." With 47 illustrations. According to Wikipedia: "The Master Key: An Electrical Fairy Tale, Founded Upon the Mysteries of Electricity and the Optimism of Its Devotees is a 1901 novel by L. Frank Baum, author of The Wonderful Wizard of Oz... The protagonist is a boy named Rob Joslyn. His age is not specified. Baum dedicated the book "To My Son, Robert Stanton Baum," who was born in 1886 and would thus have been about fifteen at the time it was published. Rob is an electrical experimenter whose father encourages him and sees that he "never lacked batteries, motors or supplies of any sort."