Page:Evolution of the thermometer.djvu/72

 used for determining the boiling-points of liquids begin also at 0° and run up to 600°, for at about this temperature mercury begins to boil. To increase the sensitiveness of thermometers they are made with cylinders instead of spheres, so that a larger surface will be more quickly affected."

Fahrenheit then gives a full account of his method of filling thermometers with liquids, a practical feature not necessary to detail in this place. The fever thermometers were known as "Pyranthropometers."

While these scanty records are all given us by Fahrenheit himself, other details are furnished by contemporary writers; Christian von Wolf describes the instruments given him by Fahrenheit thus:

The two thermometers had cylinders in place of spheres and were filled with colored alcohol. The cylinder of one was one and three-eighths inches long (12 inches to a Paris foot), thirteen sixty-fourths inch in diameter, and the lower portion ended in a sphere; the tube was six and eleven-sixteenths inches long. The scale was six and seven-sixteenths inches long and had 26 degrees, each of which was divided into four. The second degree on the