Newton's system was calibrated between the freezing point of water ( 0 degrees ) and human body temperature ( 12 degrees ); it was a coarser scale, but unlike R�mer's it was not intended for everyday use, as Newton's interest was in determining the boiling points of metals, which are not readily accessible with R�mer's system based on liquid thermometers.
12.
If the chosen macroscale length is too small then more coarse scale variables may be needed : for example, in fluid dynamics we conventionally close the PDEs for density, momentum and energy; yet in high speed flow especially at lower densities we need to resolve modes of molecular vibration because they have not equilibrated on the time scales of the fluid flow.
