two thermoelectric piles, each composed of twenty antimony-bismuth couples;

two trumpet-shaped receivers;

a small mirror for use with the graduated platform and the auxiliary rule in experiments on reflection and refraction;

two polarizers, one for reflection and the other for refraction, the former consisting of a mica plate and the latter of a stack of very thin plates of glass mounted on the rectangular frame of a burnished brass support with an inclination such that when they are attached to the bench by means of their support the inclination is that of Brewster; the device can also rotate around the direction of the incident beam and the different orientations of the incidence plane are indicated on a graduated disk on the support;

a similar device composed of a rectangular, burnished brass frame containing a stack of very thin glass plates which can rotate around an axis, thus allowing regulation of both the incident angle and the orientation of the incidence plane.