Watkins-type simple microscope
Date: circa 1760
Inventory Number: 2002-1-0059
Classification: Microscope
Dimensions:18.5 x 13 x 13 cm (7 5/16 x 5 1/8 x 5 1/8 in.)
Accessories: 1 ivory slider, 1 Lieberkühn
DescriptionA folding tripod base screws to the bottom of the tapered, octagonal pillar which ends in a compass joint, with locking screw, to support the limb. A flat mirror with beveled edge mounts with a hinge by a split pin at the bottom of the limb.
At the top of the limb is a plate holding a wheel with positions for 8 lenses. The plate has 2 holes, one for the lens in use, the other for showing its number (1-8). A Lieberkühn slips into a dovetail on the underside of the plate. (It is currently oriented the wrong way.)
The stage slides on a dovetail to a position on the 1 to 8 scale. The limb has two scales engraved on it. At the top is a scale numbered 1 to 8 descending, these numbers corresponding to the numbers on the lens wheel. Below this is a scale of numbers corresponding the the magnification of those lenses: 160000, 17689, 10000, 3949, 1600, 676, 400, 251.
The fine focus is by a rod running through the limb from a knurled wheel near the compass joint below the limb to the plate, which is guided by two rods.