"The 20th century also saw the refinement of the temperature scale. Temperatures can now be measured to within about 0.001°C over a wide range, although it is not a simple task"
I would guess that specially manufactured and expensive thermometers could achieve such high resolution in a controlled environment...
Not too likely for the broad range of temperature measurement equipment manufactured at the time...
I wonder even how systematic their QC of such manufactured items such as these was back then...
