Two encapsulated germanium thermometers have been calibrated and tested between 1.4° and 4.2°K. Within the precision of the measurements (±0.4 millidegree) no change in their calibration was found after cycling to room temperature or after temporary removal from the measuring apparatus. In this respect, the germanium thermometers were considerably better than carbon thermometers. For comparison a carbon thermometer was encapsulated and found to undergo unpredictable changes corresponding to several millidegrees under similar circumstances.