Description:
A brass split ring goes around the eyepiece of a microscope. A bracket at the back of the ring holds a pillar to which is attached the prism box. The pillar is stuck at present but presumably swung aside to permit viewing through the eyepiece without the camera lucida in place. Below the prism box is a blue filter on a swing-aside mount.
The parts of the prism box and bracket are blackened, while the rest is bright brass.
The box is made of wood, covered in black leather, and lined with purple silk and velvet.