Page:Evolution of the thermometer.djvu/14

 but in summer it descends so low that in great heat it can scarcely be seen in the tube.

"Those who wish to determine these changes by numbers and degrees draw a line all along the tube and divide it into eight degrees, according to the philosophers, or into four degrees according to the physicians, subdividing each of the eight spaces into eight others so as to make sixty-four little ones. And by this means they can determine to what degree the water ascends in the morning, at midday and at every hour. Also one can determine how much colder one day is than another, noting how many degrees the water ascends and descends. One can compare the greatest heat and cold of one year with those of another year. One can ascertain how much hotter one room is than another; one can maintain a room at an equal temperature by making the water of the thermometer stand always at a certain degree. One can test also the intensity of fevers; in short, one can know pretty nearly to what extent air is rarefied in the greatest heat, and so forth."