A Cased W. Watson & Sons Compound Monocular Microscope, circa 1891. 13-5/8 inches high (34.6 cm) (base). ...

Description

A Cased W. Watson & Sons Compound Monocular Microscope, circa 1891
13-5/8 inches high (34.6 cm) (base)

PRIVATE WEST COAST COLLECTION

"W. WATSON & SONS 313 High Holborn London 2937". Ca. 1891. A Van Heurck model most like the No. 1. Coarse focusing for main body tube and separate control for mechanical draw tube. Fine focusing on top of limb. Additional manual draw tube calibrated from 144mm to 238mm. X-Y mechanical stage with verniers to read to 0.1mm, stage clips. Rotating stage 4-1/2" dia., calibrated in degrees with a vernier reading to 5 arc minutes. Stage rotates through 242º, not 360º. Milled head rotates the stage or may be disengaged for manual rotation. Limb connected to tripod base through massive trunnions; inclination angle clamped with large lever. Substage moves on rack and pinion with unique fine focusing adjustment with calibrated milled head. Condenser is centerable and rotates on a toothed gear, flip-out filter holder, iris diaphragm, removable lenses. Additional condenser lens marked, "THE UNIVERSAL 0-4 in. 1.0 N.A. W. Watson & Sons Ltd. London 1794". 3" plano/convex mirror. Objectives in signed brass cans:
60x, "4 m/m 0.90 N.A. Tube Lth 250mm HOLOS Watson & Sons London"
6x Parachromatic, "2 in. 0.15 N.A. W. Watson & Sons London"
4x Parachromatic, "3 in. W. Watson & Sons London"
Three unsigned oculars represented to be Watson: 5x, "A"; 6x, "B"; 8x, "C KELNER";
one later 23mm nickel body with an adapter ring, "2 6x".
Original fitted mahogany cabinet with accessory drawer, 10-5/8" wide x 9-5/8" deep x 19" high.
This is a very early version of the Van Heurck model. Bracegirdle says that the second stand of the series was sn 2688 and was sold on 22 Jun 1891. Hogg, 1898 (published in 1911), p. 109, shows a cut of subject stand and describes it as "Watson's Improved 'Van Heurck Bacteriological' Microscope. Models were designated with letters beginning June, 1892. Later stands designated, "Grand", "Circuit" and "No. 1" often had the model engraved on the plate at the rear of the foot. Subject stand probably predates all these designations making 1891 a reasonable date of manufacture. "The Microscope" by Dr. Henri Van Heurck, 1898,p. 224-232, describes this stand in great detail. He also mentions the just developed series of completely new objectives, most probably the Holos series. That would mean that the preceding Parachromatic series are most appropriate for this stand. It is said that Van Heurck made suggestions to Watson for a new stand with extremely fine and stable fine focus after attempting to use a new high power Zeiss objective with a very high N.A.


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