Charles A. Spencer (Spencer & Eaton), Canastota N.Y.

The Large Trunnion microscope with lever activated mechanical stage, c. 1859

Charles A. Spencer (Spencer & Eaton). The Large Trunnion Model microscope with lever activated stage, c. 1859
Charles A. Spencer (Spencer & Eaton), Canastota N.Y. The Large Trunnion Model microscope with lever activated mechanical stage, c. 1859
Charles A. Spencer (Spencer & Eaton), Canastota N.Y. The Large Trunnion Model microscope with lever activated mechanical stage, c. 1859
Charles A. Spencer (Spencer & Eaton), Canastota N.Y. The Large Trunnion Model microscope with lever activated mechanical stage, c. 1859
Charles A. Spencer (Spencer & Eaton), Canastota N.Y. The Large Trunnion Model microscope with lever activated mechanical stage, c. 1859
Charles A. Spencer (Spencer & Eaton), Canastota N.Y. The Large Trunnion Model microscope with lever activated mechanical stage, c. 1859
with accessories

This is a fine example of the first class large Trunnion model microscope made by Charles A. Spencer (1813-1881) of Canastota New York. While this microscope itself is unsigned, the objective canisters are marked Spencer. This particular example has a lever type mechanical stage. The instrument illustrated in Carpenter and King shows the microscope with a Turrell-type mechanical stage with the knobs located under the stage. The bar-limb design of this microscope borrows features first introduced by Andrew Ross in 1843. C. A. Spencer was America's first commercial manufacturer of microscopes. He began production in the late 1830's. Around the time the microscope shown here was produced, mid-19th century, the firm traded under the name Spencer & Eaton. By around 1865, the firm was known as C. A. Spencer & Sons.

The storage case is supplied with three drawers. The top drawer contains a group of prepared slides, the middle drawer houses some unmounted specimens and documents, and the bottom drawer holds the accessories. Among the accessories are three objectives with bayonet fittings having canisters marked Spencer (1, 1 1/2, and 1/4 inch magnifications), two eyepieces with dust caps, a substage polarizer in a rotating mount, an analyzer that mounts above an objective, another analyzer with rotation that mounts above the eyepiece (not shown), a live box, a hand forceps, and knife. There are two separate substages with centering adjustments where one is used to hold an objective to serve as a condenser, while the other is used to mount the polarizer or other larger accessory. Also, there is an adapter that fits the objectives allowing them to be used with microscopes utilizing the RMS thread. The precise dating of this microscope is uncertain, but since the RMS thread standard was formalized in 1858, it is reasonable to assume that the microscope was made at that time or shortly thereafter. Accompanying the microscope is a box containing additional prepared slides.

An additional example of Spencer's Trunnion model with a different type of stage is also represented in this collection.


with polarizer

The microscope set up for polarization

with objective as a condenser

The microscope set up with an objective used as a condenser

microscope in case
storage case



The following is from Carpenter's The Microscope and its Revelations, first American edition, 1855.

Mr. Charles A. Spencer of Canastota, New York, has manufactured a microscope of great excellence, the objectives of which will bear comparison with the best of foreign construction. His common angle of aperture for 1/4 inch objectives is 135 degrees; for 1/8 inch, 170 degress, and for 1/12 and 1/16 inch, 176 degrees. This. is believed to be the largest angle ever given to an object-glass, and for sharpness of definition and power of penetration, they are unexcelled by any of foreign make.

To Mr. Spencer is due the credit of having first resolved, with lenses of his own construction, the fine markings on the Navicular Spencerii and Grammatophora Subtilissima: these minute shells have since been adopted by microscopists as test-objects for the highest powers. The Navicula Spencerii, will exhibit one set of lines with Mr. Spencer's 1/4 th-inch object-glass: both sets with the 1/8 th-inch. The Glrammatophora Subtilissima is a good test for a 1/12 th or 1/16 th.

Of several microscopes made by Mr. Spencer, two or three only will be here noticed. His first-class or best instrument is mounted on trunnions, and embraces all the acknowledged improvements, in form and stage, whereby the greatest steadiness and freedom from tremor are secured. The price of this instrument with all the accessories and a full set of object-glasses will approach $350 (Fig, 426)

The microscope was also described in more detail in the book The Microscopist's Companion by John King, 1859 where the following price list was taken:

Spencer and Eaton price_list

To get an indication of the rarity of this microscope see: An Early American Microscope in the Proceedings of the American Microscopical Society, vol. 14, No. 3, Fifteenth Annual Meeting. Part III (Jul., 1893), pp. 156-158

trunnion microscope
Charles Spencer


The following was 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.

For an additional discussion of the life and work of Charles A. Spencer (1813-1881), America's first microscope maker, see Three American Microscope Builders published by the American Optical Company 1945. An additional biography of Charles Spencer was published in the Proceedings of the American Society of Microscopists, Vol. 4, Fifth Annual Meeting (1882), pp. 49-74.


William Davis Ely

William Davis Ely (1815-1908)

Among the documents found in the storage case was a letter addressed to "Wm D. Ely Esq, No. 668 North Main St., Hartford Conn". On the inside cover of the box of slides is a note stating that the slides were given to William Ely in 1873. It is therefore reasonable to assume that this microscope was the property of Mr. Ely. At the time this microscope was made, c. 1859, there was a prominent lawyer living in Hartford with that name.

William Davis Ely (1815-1908) studied at Yale college taking courses in the Divinity and Medical schools after which he became a tutor of Natural Philosophy at the college while studying for a degree in law. He practiced law in Hartford and later moved to Providence RI where he spent his time overseeing the construction railroads throughout the North East and was also engaged in the cotton business producing yarns (among the specimens stored in the drawer of the case are various samples of cotton fabric). The Yale University Library retains an archive of some of the William D. Ely papers; A biographical sketch is available online.


Another example of Spencer's Trunnion model with a different type of stage is also represented in this collection. A microscope very similar to the one shown on this page is in the Harvard Collection. It is unsigned and is most likely one made by Charles Spencer. The form of that microscope clearly suggests it is an example of his Large Trunnion Microscope.

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