you could probably rig up a steampunk sun-following mirror positioning system by just using a shitload of math and astronomical data to pre-program a daily turning system for each individual mirror
the mirrors themselves probably(?) get hot enough that you could put a steam or Stirling engine with its hot side on the back of the mirror surface & power each mirror's sickass cog-analog pivot system
then you just need someone with a handlebar moustache and/or wild frizzy hair to ride a mechanical horse around the mirror field punching in the set points for all the mirror turners every morning, mumbling under their breath about the astronomer's numbers being slightly off and having to compensate with the mech-horse's built in calculator, which naturally takes forever as the horse can only display the numerical results by tapping its hoof
but maybe you could also do it semi-automatically and non-electronically by designing a mechanical feedback system that uses mirror surface temperature as its input data? like if the temperature drops enough, a bimetallic strip or fluid-filled piston engages a gear clutch or something
