You attached the dial thermostat to the incubator so it could rotate relative
to the (bare-wire) fixed contacts. This allows you to change the temperature
at which the light turns off, but rotating the thermometer. Which direction
of rotation will keep the bulb on longer for a higher temperature? Mark
a reference point on the aluminum case of the dial thermometer. Starting
at room temperature, rotate the thermometer carefully until the bulb lights.
Mark on the incubator box (in pencil), the location of the reference point
just as the bulb turns on. Now let the incubator heat up two degrees, rotate
the thermometer 'till the light goes out, then rotate it back carefully
until the light turns on again at this higher temperature. Mark the location
of the reference point. Continue this process for 10 or 20 degrees and you
will have a semicircle of marks on the incubator box showing incubator settings.
You have calibrated the incubator thermostat.
