In 'The Flying Machine Boys on Duty; Or, The Clue Above the Clouds' by Frank Walton, readers are taken on a thrilling adventure following a group of young boys

In 'The Flying Machine Boys on Secret Service; Or, The Capture in the Air' by Frank Walton, readers are taken on a thrilling adventure with young boys who use t

Setting the stage : technology and the series book -- Birdmen and boys, 1905-1915 -- Aces and combat : World War I and after, 1915-1935 -- Interlude : Charles A