Instruments for Personal Observations & Curiosity

c. 1850 – c. 1950

Richard Paselk, Curator

Ball-Joint Microscope

This microscope might be used at home by a student or amateur for making low and medium power observations. The magnification of this instrument is varied by changing the two button lens objectives—the lowest powers are obtained by using a single objective lens, while a combination of the lenses gives higher powers. A third, cap, lens is missing. There is a built-in disk diaphragm for controlling substage illumination. This microscope also includes a “bull’s eye” condenser lens on an articulated arm for illuminating objects from above—a common feature in the early to mid-nineteenth century.

Description

The circular, leaded brass base of this instrument is 3 1/4” in diameter, and supports a 4 1/2” tubular pillar on a ball and socket joint. There is a 1 1/2” single mirror mounted in a black oxide finished brass cell in a gimble screwed onto the pillar. The stage is 1 5/8 x 2 1/2” with a 9/16” central aperture, a four hole disk diaphragm and two stage clips held with screws and bushings (all in a black oxide finish). A 2 3/8” long bracket is fixed to the top of the pillar supports a 1 1/2” dia x 2” high fixed tube (centered over the aperture) with a double milled-head pinion. On the tube is a split ring with a ball-and-socket arm which carries a 1 5/8” condenser on a second ball-and-socket joint. The body tube is 5” long with a 7/8” cone nose (with male threads) and a rack at the back. There are two identical button objective lenses to provide low power individually or high power in combination. There was probably an additional cap lens, now missing. There are two (exposed portions bright finished except with black oxide finished eye cups) oculars 3/4” in diameter and 1 7/8” and 3 5/8” long respectively each with a knurled stop ring. A photograph of the microscope and extra eyepiece is shown below. The instrument has the original bright lacquer finish with a few small oxidation spots where the finish is gone. The microscope is 10 1/2” high when closed and with the smaller ocular in place. The microscope comes with a 11 1/2 x 5 1/2 x 4 1/16” fitted walnut? case with a holder for the extra ocular and a small compartment for extra parts (with modern replacement lid). There is a keyed pin-lock, with an inlayed ebony diamond enclosing the keyhole. The key is a custom made replacement. A photograph of the microscope in the case is also shown below.

*Similar microscopes in a number of collections are identified as of French origin, e.g.: various stands as illustrated in The Billings Microscope Collection, 2nd ed, figure 117, c. 1871 (“This type instrument appeared on the market in the late 1860’s unsigned. Hartnack of Paris is known have made microscopes ‘for trade’ and unsigned; Nachet also made a small microscope mounted on a round foot similar to this model.”), figure 125, c. 1875, and figure 417, c. 1860.

© R. Paselk 2013, Last modified 31 December 2020