Electric Motor
mercury = a heavy silvery-white metal which is liquid at ordinary temperatures (Hg)
continuous motion = motion that doesn't stop
electric current = see here (https://t.me/espedition/607)
coil = a spiral shape or a series of circles, each one inside another
paddleboat = a boat powered by steam and propelled by paddle wheels
in the course of = during
conveyor belt = a continuous moving strip or surface that is used in the process of producing goods in a factory and for transporting objects (idiomatic meaning (https://t.me/espedition/564))
pave the way for = make something possible
clunky = solid, heavy, and old-fashioned
See also
Electricity Supply (https://t.me/espedition/110)
Parallel Electrical Circuit (https://t.me/espedition/71)