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BULLOCH 'A B' MICROSCOPE

DATES: 1870's

 

The second to largest microscope that Bulloch produced, once he started to make the A 1 stand, was shortly thereafter termed the 'Congress Junior' model*, and it is likely the 'A B' stand pictured in the 1878 catalog is indeed that model, as it is described as 'similar to the large stand but smaller.' It is also described in that catalog as the 'Diatom stand' which fits its description as the 'Congress Junior'*. A cross-sectional view shows it to be quite similar to the A 1 stand, except for a thinner stage with gliding slide support instead of mechanical stage. Bulloch reports that this stage could be completely turned upside down, slide underneath, to allow the greatest degree of oblique lighting to be used. The original version of the Congress Junior would also have the same tubular mirror support with double articulating bars at the end.

This was the precursor of the later, two-pillared version of the 'Professional,' sometimes called the Professional No 1 (although Bulloch never called it a No 1, he referred to only The Professional and The Professional No 2). One unique feature of the diatom stage was two separate hold down points, each acting on a separate piece of glass on opposite ends of the slide holder; this would indeed support an upside down slide if the stage were rotated 180 degrees. I have not found a surviving example of this exact stand, hence only the diagram is shown here.

* As reported in the Proceedings of the Fourth annual meeting of the American Society of Microscopists of 1881.