COMPOUND MONOCULAR MICROSCOPE

MAKER:ANDREW PRITCHARD

MODEL:'ACHROMATIC ENGISCOPE'

c. 1854

SIGNED: 'Andrew Pritchard, 162 Fleet street. London'

SERIAL NUMBER: 560

Three stages are present, which can be slotted into the round central aperture of the fixed rectangular stage; a rectangular plain stage with two movable slide rests, a beautifully finished Turrell mechanical stage, and, unusually for a microscope of this late a date, a Bonanni spring stage of generous enough proportions to accommodate standard-size glass slides of 1 x 3 inches. The latter can accomodate the Pritchard type slide consisting of two slides, their edges bonded together with red sealing wax. Only the plain- and Bonanni stages have a thread cut into the lower end of their tubes to accommodate the substage accessory sleeve. The Bonani spring stage can accomodate slides in two slots, one above the other. This can be used for example to easily position a selenite slide under the object slide being studied.

The top plate of the Turrell stage can be rotated by hand through 360 °, and there is a bayonet fitting allowing for its removal in two positions 180° apart, so that a vial holder with the same male bayonet fitting can be secured in its place on the stage. This allows for the observation of organisms in a vial of liquid with the microscope body rotated 90° to keep the fluid level in the horizontal plane.