Monocular:  serial no. 975
prior to 1876

Binocular: serial no. 720
prior to 1876

Monocular: serial no. 1867
after 1876
(this is a rare transitional model. It has the swinging substage, but still retains the nosepiece fine adjustment)

Binocular: serial no. 3773
after 1876

The Army microscopes made after 1876 incorporate the swinging substage described in the Zentmayer patent of  Aug. 15, 1876    

The United States Army Hospital Model microscope was originally designed in 1863 for use by the U.S.A. Medical Department during the Civil War. The following is an excerpt from the Army Surgeon's Manual for use of Medical Officers, Cadets, Chaplains, and Hospital Stewards by William Grace published in 1864 concerning the Army microscope: