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HISTORY OF THE NELSON-CURTIES MICROSCOPES

MAKER: CHARLES BAKER COMPANY

THE FIRST 'NELSON' MICROSCOPE

Nelson Model

The earliest model reflecting a Nelson-Curties collaboration was a lightweight stand known, (confusingly) as the 'Nelson Model,' first described in early 1887. It was shown to the members of the Quekett Microscopical Club on January 28, 1887 by E.M. Nelson himself. It was also reported by Nelson on page 292 of the JRMS for 1887.   This microscope was hailed by Nelson as a great achievement because it was, in his view the first 'Student' microscope that was suitable for high class work, yet was not inordinately expensive. This was achieved in part through the use of a 'Campbell Differential Screw mechanism for the fine focus. It was called this because the Reverend J. A. Campbell suggested this mechanism for this use, but it was actually invented long before Campbell. This mechanism uses a screw with two different pitches, one finer than the other. The coarser end is threaded through the fixed end of the limb and the finer one drives the focusing mechanism. Because the movement is equal to the difference in the pitches, a very fine and precise movement can be achieved in a structurally strong design. This type of fine adjustment continued to be used in future Nelson stands.