Circa 1850. 8vo. 96 pp. of MS. notes in Danish, from a lecture in optics, signed "C. Hollen". Illustrated with numerous detailed diagrams and charts. Original limp blue wrappers, separated from text block, chipping along spine; text leaves lightly toned; ink stamp of "Dansk iIngeniørforenings Bogsamling" on front and rear wrapper, and scattered throughtout text.