After the milk is all in, or the requisite amount is in the vat, the
heat may at once be started and raised to some point between 80 and 86
degrees. If we set below this, the rennet works too slow; if we set
above, it is thought to work too fast--so custom has fixed upon this
range of temperature for setting, and there appears to be no valid
objection to it. But while the temperature of the milk is being raised,
and before, it should receive frequent stirrings to keep the cream
from rising, and thus becoming partially or wholly wasted. The rennet
should by no means be added until the temperature stops rising--or so
nearly so that by the time the rennet is stirred in and the stirring
stopped, because the milk begins to coagulate, a stationary temperature
will have been reached.