Divided-lens micrometer made in the early 1870s for use with the 26-inch refracting telescope at the United States Naval Observatory. A paper label on the box reads “Edw. Kahler / Manufacturer of Optical, Mathematical and Philosophical Instruments / 1807 K St. NW / Washington, D.C.” Edward Kahler (1833-1900) was a German instrument maker who was working in Washington by 1869.
Ref: United States Naval Observatory, Astronomical and Meteorological Observations Made During the Year 1874 (Washington, D.C., 1877), Appendix 1, “Instruments and Publications,” p. 38.