This book is the first detailed volume to cover the famous Norden Bombsight (NBS) which was one of the most secret weapons used before and during World War II by the United States in its bomber aircraft. Development of the NBS was started in 1922 by the Navy Bureau of Ordnance, and in 1932 the famous Mark XV was introduced. Configuration of the NBS, except for changes, remained static through its life, and its accuracy during Allied bombing runs made it one of the most important technical developments of the war. Later several attachments were devised to make it more accurate - new optics...