A current generator producing electric energy directly from thermal
energy by pyromagnetism.

Edison’s pyromagnetic generator has eight electro-magnets, lying on
eight radii of a circle, their poles facing inward and their yokes
vertical. Only two are shown in the cut. On a horizontal iron disc are
mounted eight vertical rolls of corrugated nickel representing
armatures. On each armature a coil of wire, insulated from the nickel by
asbestus is wound. The coils are all in series, and have eight
connections with a commutator as in a drum armature. There are two main
divisions to the commutator. Each connects with an insulated collecting
ring, and the commutator and collecting rings are mounted on a spindle
rotated by power. Below the circle of vertical coils is a horizontal
screen, mounted on the spindle and rotating with it.

A source of heat, or a coal stove is directly below the machine and its
hot products of combustion pass up through the coils, some of which are
screened by the rotating screen. The effect is that the coils are
subjecting to induction owing to the change in permeability of the
nickel cores, according as they are heated, or as they cool when the
screen is interposed. The two commutator segments are in constant
relation to the screen, and current is collected therefrom and by the
collecting rings is taken to the outside circuit.