The following is 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.

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This microscope, while unsigned, is an example made by Charles A. Spencer in the Andrew Pritchard style. The mechanical stage is of the Turrell type with the unusual feature of having the controlling knobs located under the stage (this type of mechanical stage was also used on a version of Spencer's Trunnion microscope).

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".

The microscope as pictured in a 1955 newspaper article:

The following was extracted from the History of medicine in New York v. 3, 1919:

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The following biographies were extracted from The National Cyclopedia of American Biography, vol. XIII, 1906.

SPENCER, Charles Achilles, lensmaker, was born at Lenox, Madison co., N. Y., Sept. 13, 1813, son of Gen. Ichabod Smith and Mary (Pierson) Spencer, and a descendant of Thomas Spencer, the first of the family in America. The line is traced through Thomas's son Thomas, through his son Samuel, his son Thomas, his son Eliphalet, and his son Eliphalet, the father of Ichabod Smith Spencer. The last named was an officer in the war of 1812. The son was educated at Cazenovia Academy, Hobart College, and Hamilton College. He displayed his natural aptitude at a very early age, making his own optical glass when only twelve years old. In 1838 he announced himself as a manufacturer of telescopes and microscopes, locating his workshop at Canastota, N. Y., and here, in spite of busmess reversals he continued to devote himself to the perfection of the achromatic telescope and microscope, later becoming the pioneer in developing the possibilities of lensmakmg as applied to the microscope. Ten years later (1848) there issued from this little shop at Canastota lenses that mystified both English and French microscopists, chiefly because of their great resolving power. He had succeeded in making the microscope objectives so effective as to accomplish results in " definition " before unknown, surpassing the efforts of the best European opticians and upsetting their claim that they had obtained the largest angular pencil of light that could be passed through a microscope object glass. He had proved by actual construction that the angle of aperture in these higher power objectives could be greatly increased, and with it their defining and resolving powers. The English makers charged Mr. Spencer with the I knowledge of some mode of working glass as yet unknown to other opticians, and while this was partly true, his chief success was due to his tact in figuring the lenses so as to balance the aberrations, a process so delicate that it would have availed no one not possessed of the same skill to copy curves. From this time forward Mr. Spencer kept steadily in advance of foreign opticians as to angle of aperture; and his microscopical objectives were pronounced the best in the world. In the fall of 1873 a disastrous fire broke out in Canastota, destroying his shop with nearly all his tools and machinery (the accumulation of many years), together with a large amount of finished and unfinished work. Crippled, but not disheartened, he continued his work under difficulties, and in 1875 entered the employ of the Geneva Optical Works, Geneva, N. Y., where he worked for two years. During 1854-56 his business was conducted under the firm name of Spencer & Eaton, his partner being A. K. Eaton, and in 1877 he started the firm of C. A. Spencer & Sons, with his sons Herbert R. and Clarence Leslie Spencer, and Major O. T. May, his son-in-law. This association lasted for three years, when the health of Mr. Spencer, Sr., failed to such an extent that he gave up active work. On Aug. 10, 1881, Charles A. Spencer was elected one of the first honorary members of the American Society of Microscopists. He was married July 10, 1838, to Mary Morris, daughter of Lonson and Hannah Stilwell, of Manlius, N. Y., and had six children. He died at Geneva, N. Y., Sept. 28, 1881.

SPENCER, Herbert Ruthven, lensmaker, was born at Canastota, Madison co., N. Y., Nov. 1, 1849, son of Charles Achilles and Mary (Morris) Spencer. He was educated only in the common schools. He early developed a fondness for scientific study and he cultivated a habit of close observation. He became imbued with the atmosphere of genius that surrounded him, and while yet a mere lad began to make lenses on a lathe of his own construction, equaled in those days only by the lenses of his father and his father's coworker, Robert B. Tolles. Having thoroughly learned the art of lensmaking, he became a partner with his father after the dissolution of the firm of Spencer & Eaton. Fire destroyed their shop at Canastota in the autumn of 1873, but they managed to make both ends meet for two years longer, when father and son entered the employ of the Geneva Optical Works. In 1877 they set up another shop in the barn and made lenses, under the firm name of C. A. Spencer & Sons. Some of these came into the hands of F. A. P. Barnard, president of Columbia College, one of the U. S. commissioners to the Paris exposition of 1878, and so convinced was he of their excellence that he entered them at the fair without the knowledge of the Spencers. To the surprise of European opticians and the gratification of the makers these lenses won the gold medal for excellence and superiority. These objectives are said to have been the handiwork of Herbert R. Spencer. In 1880 he began business under his own name and continued to make microscopes, telescopes and objectives, at Geneva, N. Y., for nine years. In 1889 he removed to Cleveland, O., and established the H. R. Spencer Optical Co., which he conducted for three years, when he removed to Buffalo, N. Y. There his firm was known as the Spencer-Smith Optical Co., until 1895, when it was incorporated as the Spencer Lens Co., Mr. Spencer always retaining the active superintendency of the shop. The Spencer Lens Co. is known throughout the world as producers of the highest grade of microscopes, microscope objectives and other accessories, as well as other optical instruments and laboratory apparatus. After Mr. Spencer's death the company secured the services of Dr. Hermann Kellner, who had obtained a thorough training in the science of applied optics in the great Zeiss works at Jena, as their scientific director, and Carl F. Dieckmann, of Gottingen, became superintendent of their shop. Under this new control .the company reorganized the business, adopting for the first time in the United States the same methods of precision in mechanical construction as are used in the best scientific works of Europe. The officers of the company are: Dr. Roswell Park, a famous physician and surgeon of Buffalo, president; W. H. Glenny, vice-president, and Henry R. Rowland, secretary and treasurer. In the direction of applied optics Herbert R. Spencer ranked with Leuwenhoek, Amici, Abbe, and other great Europeans, with his father, and with Robert B. Tolles, who were the best of American lensmakers. His skill made possible many discoveries in medical science that could not otherwise have been leached. He was of a kindly disposition, ever generous toward the attainments of others, and whatever he himself did, always admitted that he could do better. He was a member of the American Microscopical Society, and a fellow of the Royal Microscopical Society of London. England. He was married Sept. 6, 1887, to Anna Lena, daughter of Jacob and Margaret Wheeler. He died in Buffalo, N. Y., Feb. 7, 1900.

For an additional discussions of the life and work of C. A. and H. R. Spencer,  see Three American Microscope Builders published by the American Optical Company 1945.