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Compound achromatic microscope, stand ‘Kima’

Maker

WATSON & SONS

Country

United Kingdom

Signature

“KIMA” / W. Watson & Sons Ltd. / London / 66646

Category

Microscopes

Optical 1

Compound

Optical 2

Achromatic

Size of the microscope (h x b x d)

31 × 13.5 × 17 cm

Provenance

Chelsea, Polytechnic - Pharmaceutical Department

Inventory number

SM 13

Description

A good example of a pre-war student microscope, with a cast iron horseshoe-shaped foot with pillar and a dito limb that hinges in the pillar. There is a simple stage, below a condenser with its adjustable stop and a holder for filters. There is a mirror in a swing arc on a limb. The limb ends in a double block with the coarse and fine adjustment acting on the body tube, which has a triple nosepiece changer.
The only eyepiece is signed ‘Busch’, it must be a replacement. Its focal length is 19.92 mm, the magnification is 12.55×.
There are two objective lenses, signed ‘2/3 Argus No.187396’ and ‘1/6 Argus No. 187174’. Both have been investigated using the Bleeker microscope with a 160 mm body tube. The ‘2/3’ with a 10× Huygenian eyepiece, the ‘1/6’ with a 5× Huygenian eyepiece.

Objective 2/3 1/6
Focal length (mm) 16.16 3.63
Magnification 96.43 238.97
Numerical aperture 0.26 0.74
Resolving power (µm) 1.3 < 0.8

The ‘2/3’is good, all its aberrations are well corrected. The ‘1/6’ is in good condition as well, it only showed a trace of coma. It resolves the Pleurosigma angulatum diatom into dots.