Even a low tech thing like this brick fire box needs a little 'lectric these days. (look at all those wires.)
There are 6 temperature probes that help to find out how deeply the heat has penetrated the masonry. Three are in the floor and three are in the dome. They are 1" from the surface, 4" from the surface and abour 10" from the surface (or in the brick, between the brick and concrete cladding, and on the outside of the concrete cladding, respectively). here's the hole in the oven floor through which the wires will be routed.
The view from inside the oven, probably the last time this view will be possible.
All of these are hooked up to a multiple readout meter that allows me to switch from one reading to another to another. (It's 67 degrees inside that brick!)
The wires are routed through the catacombs underneath the oven for the floor probes and through the (eventual) outer insulation for the dome wires all to the meter which will be mounted to the right of the oven door in a little nook that I will create whenever I get to these decorative (i.e. non-functional) walls.