The parts of the exemplar on display, which is the one that was most widespread in the 19th century, are:
· the brass tube consisting of two pieces, one a truncated cone (diameters 9 and 6 cm; length 14.5 cm) and the other a cylinder which slides, with an extension of 11 cm, inside the narrower part of the former;
· the shelf for objects on which the support for the slides moves; it is burnished brass, at the centre it has a circular aperture and lies with four pins with spring spacers on another burnished brass plate attached to the narrower end of the tube;
· the objective, composed of a system of converging lenses of short focal length held by a staff which, by means of a rack screw, allows it to move towards or away from the slide.

At the wider end, the microscope tube is threaded so that it can be screwed onto the heliostat and it has a converging lens which, by completely covering the aperture, captures the sunlight reflected by the heliostat mirror, making it converge onto one lens placed at the end of the tube which, in turn, makes it converge on the object. ...continues