Notes, in English and occasional Russian, on the physics of air, principally pressure differentials and sound propagation. Topics include a lengthy discussion of the function and gross anatomy of the ear, barometrical measurement of height; published chart of comparative altitudes of famous mountain peaks, and the overall constitution of the atmosphere. The second half of the volume covers ballistics, mostly: diagrams, calculations, and records of artillery trials. A short, unrelated section at the end includes a piece on undulation of elastic fluids.