It is now possible, thanks to their researches, to estimate a temperature of 2000 deg.

C.to within about 5 deg.

Ten years ago a similar approximation could hardly have been arrived at for a temperature of 1000 deg.

C.
Sec.6.DERIVED UNITS AND THE MEASURE OF A QUANTITY OF ENERGY It must be understood that it is only by arbitrary convention that a dependency is established between a derived unit and the fundamental units.

The laws of numbers in physics are often only laws of proportion.