The solar microscope body tube has three fixed lenses (B–D) and a series of six "objective" lenses on a sliding holder (A). In addition, there are two rack and pinion focus mechanisms.

The three main lenses are:

B: "Between lens": biconvex, dia = 8mm, f=32mm
C: Field lens: plano-convex, dia=28mm, f=65mm
D: Condenser lens: biconvex, dia=48mm, f=230mm

The glass of lenses C and D has a green tint.

Slide samples are mounted between lenses "B" and "A".

Samples in glass phials would have been mounted in the depression under lens "B".

Image focus was adjusted using the thumbscrew near lens "B". Tube length was adjusted using the thumbscrew near lens "C".