A: Bulb containing mercury attached to a glass tube of narrow diameter. Thermometer has Celsius scale with 20-30 degree range with major divisions every 1 degree and minor divisions every 0.1 degree.
B: Protective cardboard tube for the thermometer (not digitized).
Total immersion thermometers are designed with scales which indicate actual temperature when the bulb and the entire liquid column are exposed to the temperature being measured. In practice, a short length of liquid column (usually one-half inch) is permitted to extend above the surface of the liquid being measured to allow reading of the thermometer. Most total immersion thermometers can also be used in a condition of complete immersion, wherein the entire thermometer is exposed to the temperature being measured, as with a thermometer inside a refrigerator, freezer, incubator or other chamber.