Charles A. Spencer
Charles A. Spencer was an American scientific pioneer and inventor, who is widely believed to have developed the first American-made achromatic objective microscope. He was born in 1813 in Madison County, NY  and died in 1881.
Spencer’s first microscopes were available for purchase in 1838. Previous to Spencer’s invention, European manufacturers held a monopoly on research-quality microscopic equipment. At least one of Spencer’s microscopes survives and is currently held by the Smithsonian Institution.
In 1854, Spencer formed a partnership with A.K. Eaton for the manufacture of high quality microscopes, which was located in Canastota, NY, USA. This partnership would prove successful, with back-orders from all over the world reportedly exceeding $20,000 US in the currency of the day.
A “crippling” fire in 1875 however, would lead to the failure and dissolution of this original partnership. Following a move to Geneva, NY and a brief partnership with Geneva Optical Works, a new business was founded that included Spencer’s sons in 1877 called “Charles A. Spencer & Sons.” 
Honors and tributes
Despite not seeking recognition for their work in the trade, in 1878 the Spencer’s microscopes would receive the Paris Universal Exposition Exposition Universelle (1878) highest award, the Grand Gold Medal, for excellence in their optics.
In 1884, ground was broken in Rochester, NY for the foundation of a monument to Spencer and his peer, Robert B. Tolles to provide an enduring honor of their achievements in American microscopy, and the scientific advances that grew from it.
A memorial fund was also established as an endowment, which would grant "not more than $100" each year, to be used for research purposes by the recipient.
In 1895, Herbert R. Spencer continued his father's work with the establishment of the Spencer Lens Company, based in Buffalo, NY. The company was later purchased by the American Optical Company. In 1967, Warner Lambert Pharmaceutical acquired the company  which, after changing hands several times, ultimately came to be known as Reichert Technologies, Inc. In 2011, the company became a part of AMETEK.
- "Memoir of Charles A. Spencer". Wiley on behalf of American Microscopical Society. JSTOR 3220512. Missing or empty
- Charles A. Spencer. "Collection of Historical Scientific Instruments". Harvard University.
- "Spencer Microscope". Smithsonian Institution. Retrieved 2015-03-04.
- Khanna, Pragya (2008-01-01). Cell and Molecular Biology. I. K. International Pvt Ltd. p. 35. ISBN 978-81-89866-59-4.
- Elliot, L.B. (1900). "Life of Herbert R. Spencer". Journal of Applied Microscopy and Laboratory Methods. Bausch & Lomb Optical Company. 3: 757.
- Secretary (1900). "Necrology". Transactions of the American Microscopical Society. American Microscopical Society. 21: 254.
- Krauss, William C. (May 1900). "The Debt of American Microscopy to Spencer and Tolles". Transactions of the American Microscopical Society. Wiley on behalf of American Microscopical Society. 23: 20. JSTOR 3220933.
- Gallaway, T.W. (April 1916). "Grants from the Spencer-Tolles Fund". Transactions of the American Microscopical Society. Wiley on behalf of American Microscopical Society. 35: 81–83. JSTOR 3221560.
- "Spencer Lens Company". The President and Fellows of Harvard College. Retrieved February 21, 2018.
- "Investigating the Origins of a Spencer Monocular Microscope". UTHSC Libraries. Retrieved February 21, 2018.
- "The AO Stereo Microscope; American Optical - A Collectors Treasure". MicroscopeMaster.com. Retrieved February 21, 2018.
- "History & Heritage". AMETEK, Inc. and Reichert, Inc. Retrieved February 21, 2018.
- "AMETEK Acquires Reichert Technologies". PR Newswire Association LLC. Retrieved February 26, 2018.