Not wishing to seem 'clever' Eggy, but I'd be interested to know what thermometer you use to measure the temperature in Arillas?
I am currently working in a UKAS Accredited Laboratory where we measure, and calibrate, thermometers.
In the course of my work, I warm up mercury to its melting point, at one end of our scale, and cool down zinc to its freezing point at the other end.
Respectively -38.8344 and 419.5270 degrees C
At NPL in Teddington, I enjoyed being able to make use of the equipment.
I get concerned if my 'Reference Thermometer' shows a difference of +/- 0.003 degrees C to the 'Set-Point' of the 'Stirred Liquid Baths'.
I use these baths to calibrate thermometers, I create UKAS Calibration Certificates for them.
I'd like to know what thermometer you use, and if it has a Certificate?
If I get a chance, I'll bring a meter with a readout resolution of 0.1 degrees C next week.