Very Good Condition. Softcover, 12 pages - plus 6 pages laid-in, with photographs on back of each page, written for The Mentor by by Floyd L. Darrow, Illustrations for the Mentor vol 7 No 14 No 186, 1919 Includes:
Article 1 Manufacture of Optical Glass
Article 2 Telescope Mirrors
Artical 3 Photographing at distance
Article 4
the Ultramicroscope
Article 5 The Spectroscope
Article 6 The Periscope
VERY HARD TO FIND.