The microscope in the 1894 photograph of Peck's office is currently in the New York State Museum History Collection (id No. 74.39.1) It was manufactured by J. Zentmayer of Philadelphia and equipped with 1 in (10x) and 1/5 in. (50x) objectives by William Wales of Fort Lee, New Jersey. A letter from Wales indicates that he suplied the complete microscope on December 6, 1868. It was donated by Loise C. Peck in 1974. It was the instrument used by Peck throughout his career until 1913.

This field microscope with missing parts was found in Peck's herbarium and is presumably the one he used prior to the purchase of the Zentmayer pictured above. It was supplied with a metal base, but was made to be mounted on the outside of the fitted, walnut case for use. A letter in Peck's files makes reference to losing parts on a trip to the Adirondack Mountains.