There are three objective lenses: two are Leitz and probably original. The third is a Carl Zeiss lens of intermediate magnification.

Leitz 3x objective disassembled.

Leitz 3x lens

Leitz high NA (1.30) oil immersion objective. 1/12 magnification (appx 60x)

Carl Zeiss lens. 0.18NA, probably 10–20x magnification

The front lens elements of the Carl Zeiss objective appear stackable, similar to the Chevalier and Schienck. It is unlikely however, they were designed work in any arrangement other than shown. After 1865/70 Zeiss or Leitz produced only a very few objectives with lenses that were intended to be used disassembled. The optics of these lenses were numbered accordingly. The Zeiss lens of this microscope is numbers only with "0.18", which is probably the NA.
After 1880 only microscopes for low magnification used disassembled objectives. (Thanks to Timo Mappes).