The book titled ""Description Of Lewis Depression Position Finders: Model Of 1907, Classes AA, A, B, C, D, E, F, EE, DD, DM, And DM 1 (1917)"" is a comprehensive guide to the Lewis Depression Position Finders. The book was written by the Office Chief of Ordnance and was first published in 1917. The Lewis Depression Position Finder was a device used in artillery to determine the position of a target based on its angle of depression. The book provides...