Watson Van Heurck Microscope

In 1891 Watson introduced the Van Heurck model of its precision Edinburgh microscope.  It was named for Henri van Heurck, the famous Belgian diatomist.  The edition came in three model sizes, the No.1, the Circuit Stage, and the Grand.  This is the No.1. All models are of equal quality but with varying accessories and features.  The instrument was exceptionally well received and in great demand by scientists who required the highest degree of precision adjustment.  Large Van Heurck editions, such as this, are quite rare today, particularly in such fine working condition.  The microscope is signed on the stage, "W. Watson & Sons, 313 High Holborn, London, 9788", the serial number dating the instrument to circa 1907.  The main focus and first stage draw tube is by rack and pinion.  Sub-stage fine control and fine focus is by thumbwheel-lever, and the two draw tubes have scales for ease of setting tube length.  Tube length is adjustable to accommodate both the short tube Continental and long tube English objectives.  The microscope has a full 360 degree rotating mechanical stage with thumb-wheel X/Y control and vernier scales to the X, Y, and rotation and a slice clamp with clips.  There is also a pair of fine controls to center the stage. A large knob to the right rear of the stage controls a very fine, up/down focus adjustment of the condenser.  The centering sub-stage has thumbwheel controlled rack & pinion adjustment and holds a lever-operated iris and swing-out filter holder with RMS threads for the condensers.  The plano-convex mirror is on a swing-out limb for oblique illumination.    All and all, this microscope has more fine adjustment controls that any of its contemporaries, and was heralded by van Heurck as the best microscope for extremely fine work.  If you like to fiddle with an instrument, this one is for you.  The optical system is comprised of a quadruple nosepiece and five original Watson parochromatic objectives with matching signed brass canisters: a 1/6", 2/3", 1", 2", and a 6mm Holos.  A top-hat Holos eyepiece, and and addional insert to accomodate conventional oculars, a micrometer eyepiece, a 20x , 12x, 10x, 8x, 7x, and 6x eyepieces.  The sub-stage accessories has a universal condenser, and an additional Holos immersion parabolic oil condenser top.  There is also a nicol prism polarizer with a nosepiece analyser with brass caps, a live box, and wet trough. the microscope is finished in lacquered brass with black japanned brass.  The original mahogany case has a metal carry handle, lock and key.  The microscope is in excellent working condition, mechanically and optically, with all original finishes. Its imposing original design, large scale, and extensive precise controls contribute to making  it one of the greatest microscopes of all time.

Item 1492

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