Aside from the obvious missing enclosure, the Foucault Photo-Électrique device is also missing the projection lens doublet (B: eyepiece) and the diaphragm (A).
From: 1886 thesis by Jean-Georges Bernard on the ‘History of the microscopes and what medicine owes to them’ (thanks to Jeroen Meeusen for this reference)
From: 1886 thesis by Jean-Georges Bernard on the ‘History of the microscopes and what medicine owes to them’ (thanks to Jeroen Meeusen for this reference)