From Carpenter's The Microscope and its Revelations, first American edition, 1855.

A very efficient microscope, is one known as the "Pritchard form:" this instrument has been somewhat modified by Mr. Spencer, and where a less expensive instrument than either of the others is desired, this one will be found a good working instrument, and available for all purposes of anatomical study. The cost of this form, with object-glasses as high as the 1/8 th, with the usual accessories is from $125 to $150.

This microscope, while unsigned, is an example made by the Spencers in the Pritchard style. The mechanical stage is of the Turrell type with the unusual feature of having the controlling knobs located under the stage. This instrument formerly was the property of the now defunct Brigham Hall Hospital at Canandaigua NY (founded by Drs. Robert D. and George Cook in 1855), an institution established for the treatment of "Mental and Nervous Diseases".

For a discussion of the life and work of C. A. and H. R. Spencer, America's first microscope makers,  see Three American Microscope Builders published by the American Optical Company 1945.