Optics of the Adams Variable compound microscope: A: Objective; B: Martin "Between Lens"; C: Field; D: Eyelens. All optics are biconvex, simple lenses.
Diagram of the position of the lenses of the Adam Variable microscope. Distances between lenses are as follows:

A-B: 10cm
B-C: 10cm
C-D: 4.5cm

Vertical lines indicate the extent of the two drawtubes.

Dia f
Eyelens 16mm 30
Field 28 70
Between 19 110