The Bonanni spring stage is press-fit into the lower brass platform. Note the recessed circle characteristic of later Culpeper models.

The spring stage is fixed in place with a modified bayonet mount. Marks on the stage and platform align the stage.

This accessory device may have been used to support a stage forceps or fish plate. It is fixed in place with a locking mechanism. Pulling the tab engages the mechanism.

Below the platform is a threaded brass extension. There are no optics in this tube, but some Culpeper models used an ivory cone threaded to the extension to control transmitted light to the sample.