COMPOUND CONTINENTAL MICROSCOPE

MAKER: EDMUND HARTNACK

MODEL: 'VII' or 'Grand Model'

SERIAL NUMBER: 19455

c.1880's(?)

SIGNED ON THE MICROSCOPE: 'E Hartnack & Co., Paris & Potsdam'on the optical tube

The pinhole diaphragms were one of the earliest methods of reducing the diameter of the light beam directed towards the specimen from under the stage. Although of limited value, they were relatively inexpensive to produce and remained popular, especially by German manufactures even into the 20th century. The device consists of a housing that fits into a substage ring. The center of the housing has a smaller ring that holds any of the different size pinhole cylinders. One of the disadvantages of this device is the need to remove the entire housing to change the diaphragm.