Practical physics
A 1922 secondary-school physics textbook by Robert Millikan and Henry Gale, issued by Ginn and Co. of Boston for American classroom use. Illustration is a stacked pair of press halftones from Underwood & Underwood showing a large twin-engine biplane on grass in side and three-quarter views, useful for coarse-screen photographic texture, aircraft silhouettes, and strut-and-wire lattice structure.
