The Chambers’ Micromanipulator (1921)

The Chambers’ Micromanipulator was a reliable, simple, and flexible instrument. Its success contributed to making its inventor, Dr. Robert Chambers (1881-1957), a leading figure among cytologists. Manufactured and improved by the Leitz Company, it remained in production for over forty years.

The Chambers’ micromanipulator was, in many respects, an evolutionary improvement on Marshall A. Barber’s pipette holder. For at least a decade before its invention, Chambers and his colleague G. L. Kite performed cytological research using Barber’s instrument at the Marine Biological Laboratory in Woods Hole Massachusetts . [Kite 1912, 564; Kite and Chambers 1912, 640] They were the first to apply the instrument, originally devised to isolate bacteria, to the more challenging task of investigating the microstructure of the living cell—a practice that Chambers dubbed “the microvivisection method” in 1918. [Chambers 1918, 121]

This form of investigation exposed the limits of the screw-actuated carriage mechanism of Barber’s pipette holder. It prompted several researchers, including Chambers, to attempt to improve it.  Such tinkering led Chambers to invent a new hinge-spring mechanism that was significantly simpler and more precise. In Chamber’s mechanism, screws forced apart rigid bars connected at the opposite end by hinges of spring steel. This largely avoided the major flaw in Barber’s instrument: the rapid wearing away of bearing surfaces due to friction.

As in Barber’s instrument, mechanisms were combined in a single “movement” to guide a tool tip along three axes. In Chamber’s system, the range of motion of the tool tips described a small section of an arc of a circle between three to four inches in diameter. In practice, this curving motion was negligible as the mechanism had only 3mm of travel and the tips typically travelled less than 1mm in normal use. [Chambers 1921, 412]

Chambers Mechanism

Two illustrations of a single “movement” (operating mechanism) of the Chamber’s micromanipulator. The image on the left is from the patent, approved in 1925. It depicts a pre-production version that attached directly to the microscope stage. The image on the right is a schematic illustration of the mechanism that often accompanied printed descriptions of the instrument.

Chambers first described his micromanipulator in 1921 in the journal Science.  This early instrument was probably made in a workshop at Cornell University and was initially available in two forms: a version that clipped to the microscope stage like Barber’s pipette holder, and a more complicated version that—like later commercial models—bolted to a solid base which also supported the microscope. Users had the option of purchasing one or two movements. One was sufficient for simple microdissection and for the isolation of individual microorganisms. Two mechanisms were necessary for more complicated tasks. More movements could be added to later production versions of the instrument. [Chambers and Kopac 1950, 503]

Chambers pre-production

Chambers’ pre-production micromanipulator  as presented in his 1922 papers. Images on the left show the stage-mounted version. The image on the right shows the more elaborate version mounted on a solid base. Two images show rods screwed into threaded sockets in the control screws to provide more precise control. The image on the left shows a flexible shaft attached to one of the vertical controls. This isolated the mechanism from accidental movement and moved the control closer to the operator.

Chambers_Needham 1925

Joseph and Dorothy Needham’s version of the Chambers’ Micromanipulator, commissioned from the Cambridge and Paul Scientific Instrument Company, differs strikingly from Chambers’ own design and the production version that would soon appear. It looks to have been gorgeously finished and must have been quite expensive. [Needham and Needham 1925, 265]

Chambers’ instrument incorporated Barber’s inventions such as the moist chamber (shown on the microscope stage in the image above) and the use of a “hanging droplet” of liquid to contain the sample. During the few years between Chamber’s first description of the instrument and its commercial availability, it seems to have partially replaced Barber’s Pipette Holder as a research instrument. In England, for instance, biochemists Dorothy and Joseph Needham—the latter would become known to historians of science for his work on China—commissioned a version from the Cambridge and Paul Scientific Instrument Company. They used it to perform microinjections of colour-changing dyes in order to chemically test cell metabolism. [Needham and Needham 1925, 263-265]

Unlike Barber, Chambers made it clear from his first publication that he was seeking a patent on his invention of the hinge/ spring mechanism. [Chambers 1921, 412] This patent arrived in 1925, around the time that the instrument was first manufactured by the Leitz company in Wetzlar, Germany, a major manufacturer of optical equipment with considerable facilities for research and development.

Into Production

The advantages of this collaboration with an established manufacturer can be seen in the production version of the instrument. The earliest catalogue from 1926 reveals that laboratory improvisations in the pre-production instruments of 1922—for instance a length of bent tubing clamped to the base of the instrument as a mount for a syringe used for microinjection—had been replaced by sturdy machined parts. Later catalogues reveal that the instrument was actively improved throughout the 1930s and beyond.

Chambers Production

Two trade literature depictions of the production version of the Chambers’ micromanipulator. The image on the left is from 1926—likely the first catalogue to depict the commercial instrument. The image on the right is from 1930. Many aspects of the instrument had been modified in the interim.

 

Inverted microscopes_McClung 1950  p506

A later production version of the Chambers’ micromanipulator used with the Leitz inverted microscope. [Chambers 1950, 506]

Industrial production transformed the Chambers’ micromanipulator into a commercial laboratory system. Existing microscopes, illuminators, and other apparatus—in some cases modified to suit micrurgical work—were listed alongside it in a special catalogue. Ordering from Leitz, researchers could furnish a laboratory with nearly everything needed for a given task, be it the isolation of microorganisms or the critical examination of cell structure.

The Leitz commercial laboratory contributed to the development of this system, creating, for instance, a special moist chamber and condenser for dark field work. Around 1933 (perhaps slightly earlier) Leitz developed, at Chambers’ suggestion, an inverted microscope to be used with the micromanipulator. This permitted the use of a moist chamber in which the sample-containing droplet was placed on the floor of the chamber rather than hanging from the roof. [Coutts 1933, 61]

Lindegren coarse adjustment 1933

Contributions from the research community: The solid bracket at the bottom of the image was developed by W. Wright and E. McCoy and produced by Leitz. A standard Chambers movement is bolted to the bracket. This illustration shows the addition of a separate mechanism, developed in 1933 by Carl C. Lindegren, which added a coarse horizontal adjustment that made it easier to initially locate the tool tips under low magnification without accidentally touching the sides of the glass chamber. [Lindegren 1933, 242]

A growing number of researchers who used the instrument also contributed to its development. Leitz sold steel brackets, invented in 1927 by  W. Wright and E. McCoy, that permitted the entire micromanipulator mechanism to be slid away from the microscope stage in order to make the process of isolating microorganisms more efficient. [Wright and McCoy 1927, 795] Leitz produced a precision needle holder, developed by Dr. Richard Frank, a member of Chambers’ Cornell lab, that made it much easier to replace microtools . [Chambers 1929, 57] Leitz also sold a machine for pulling glass microtools, developed by Delafield Du Bois of New York University in 1931, that greatly simplified their production. [Chambers and Kopac 1950, 513]

Obsolescence

Chambers’ Micromanipulator seems to have remained in production into the 1960s—possibly later. [El-Badry 1963, 69] It is not clear how long it was produced by Leitz, which had developed the more elaborate Lever-Activated Micromanipulator. It was, however, produced in this later period by the United States by the Gamma Scientific Company. This may have been the result of a breakdown of patent arrangements during the Second World War.

By the 1950s, it must have been clear that Chamber’s Micromanipulator lacked certain features that one could find on newer instruments such as De Fonbrune’s pneumatic micromanipulator or Leitz’s lever-activated model. Such refinements allowed a more granular control over the movement of the mechanism’s range of motion under different levels of magnification. This allowed the user to control the tool tips more easily as the field of view grew more confined under higher magnifications. Chamber’s instrument, had one set of controls for coarse movement, and one for fine movement, in each axis.

This inconvenience can be seen through efforts by other researchers to circumvent this limitation—Carl C. Lindgren’s modified horizontal coarse adjustment shown in the image above is one example.  A further modification, this time to the vertical controls, was described in 1950 by Milan James Kopac (1905-1989) of the Department of Biology at New York University. Kopac cited a tendency for the existing coarse vertical control to eventually become “loose from wear” and hence subject to vibration. He also faulted the arc-shaped path of the vertical mechanism which moved the tool tips out of the field of view as they were adjusted. [Kopac 1950, 233]

Kopac’s solution was to attach the X and Y mechanisms of the Chambers  mechanism to a Bausch & Lomb microscope with the body tube removed. The coarse and fine rack and pinion adjustments of the microscope replaced those of the standard model. Kopac’s modified instrument was produced and sold by Gamma Scientific Company which also manufactured Chamber’s instrument. [Kopac 1950, 234]

Kopac modificaion 1950

Kopac’s modified version of the Chambers’ Micromanipulator manufactured by the Gamma Scientific Company.

Chambers, long a dominant figure in his field, was not entirely satisfied with Kopac’s correction. A year later, he published an article entitled “A Basic Feature of the Chambers’ Micromanipulator” in which he defended the existing vertical adjustment. He claimed to have previously tried and rejected Kopac’s solution, though he acknowledged that it added a “much needed course adjustment.” Insisting that the existing mechanism was sufficient, he provided instructions on setting up the instrument in order to reduce the curvilinear motion of the tool tip during vertical adjustment. [Chambers 1951, 399]

Chambers was then about seventy years old and his instrument had been around for about thirty. The exchange is curious given that he and Kopac seem to have been close. They had collaborated for decades beginning in the 1930s when Kopac earned a postdoc to work with Chambers at New York University. In 1748, Kopac had established the Robert Chambers Laboratory for Cellular Microsurgery at NYU. The episode, no doubt, shows the extent to which Chambers’ associated his role as a leading cytological researcher with the effectiveness of the tool that he had created.

At least two examples of this instrument survive. The first, likely made in the late 1920s or very early 1930s, is in the instrument collection of the University of Toronto. The second, more worn and corroded than the U of T instrument but retaining several parts that are missing from the latter, is in the collection of the scientific instruments of Erst Leitz at Leica Microsystems GmbH. There are probably many more out there. If you know of one, I would very much appreciate some photographs.

Thank you to the archivists who provided information on this instrument, especially Jim Roan at the National Museum of American History and Rolph Beck at Leica Microsystems.

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