Buffalo 15, N. Y. American Optical Company, Scientific Instrument Division [ no date ]. 207,  pages. 8vo. No date but circa 1940s/50s. Publisher's blue cloth. Spine faded, corner tips bumped, minor wear throughout. Very Good. Cloth. 
A useful catalogue for the collector of these instruments and anyone who wants to use an instrument from this timeframe. It allows the practitioner to determine what accessories were supposed to be present with the instrument as manufactured, specifications, etc. Many nice illustrations as well. A standard reference for anyone interested in Spencer / AO instruments.