[time-nuts] What do people use for measuring temperature?

[John Ponsonby]

Have any time-nuts got any data on the long term stability or drift rates/ageing characteristics of thermistors? I am concerned with  ability of holding temperature constant at the milliK level for years. I reckon that if one can measure it one can control it. Conversely if one can't measure it, because of the instability of the sensor,  one can't control it.
John Ponsonby