Focusing the Culpeper microscope was a matter of sliding the microscope tube body inside the cardboard outer tube.
Green covering is vellum
White mottled covering is dyed shagreen
The objective nosepiece extends from the base of the body tube through a central hole in the brass top platform (below). Focusing moves the objective closer or further from the sample.
Other Culpeper microscopes of the same vintage have numbered rows of dots on the body tube. These rows correspond to numbered objectives. The Culpeper microscope in the Golub collection has no numbered rows; only vertical gold lines (above L).

The Culpeper instrument shown here is from the microscope collection at the University of California, San Francisco.

Brass upper platform. The objective nosepiece extends through the hole.