Stephenson:Neal:Quicksilver:4:...On Sir Isaac Newton's temperature scale... (Alan Sinder)
From the Quicksilver Metaweb.
... On Sir Isaac Newton's temperature scale, where freezing is zero and the heat of the human body is twelve, it is probably four or five. If Herr Fahrenheit were here with one of his new quicksilver-filled, sealed-tube thermometers, he would probably observe something in the fifties. But this sort of wind, coming as it does from the North, in the autumn, is more chilling than any mere instrument can tell. ...
Isaac Newton (around 1700) ... applied his genius to many different problems, including the concept of temperature. Lacking any better idea Newton started ranking things in order, from the coldest to the hottest, using the intuitive idea we all have for "hotness," ie hot things burn your fingers. After a bit of work Newton had a list of about 20 items that started with "cold air in winter" and finished with "glowing coals in the kitchen fire." Each item in his list was "hotter" than the one before it. Newton could now say "how hot" something not on his list was simply by saying "as hot as my body" or "as hot as boiling water" or "in between my body and boiling water," and so this list was a perfectly useable temperature scale that allowed him to describe the temperature of something to someone else as long as they both agreed on what the list of standard temperatures was. Just why he chose 33 "linseed oil" degrees for boiling water isn't clear, but that's what he did, and he called the instrument he had developed a "thermometer."
For more on Newton's scale see: https://en.wikipedia.org/wiki/Newton_scale.