MARTYN F. CHILLMAID / SCIENCE PHOTO LIBRARY MARTYN F. CHILLMAID / SCIENCE PHOTO LIBRARY
Medical thermometer. This thermometer uses the thermal expansion of mercury (silver liquid) to measure body temperature. The mercury expands from the bulb at left, rising up the scale at right. The scale here is in degrees Celsius, and is calibrated so that the thermometer can be used to measure body temperature. The red number marks normal human body temperature (37 degrees Celsius). A rise in body temperature often indicates a fever, where the rise in body temperature is part of the defence mechanism against an infection.
Model release not required. Property release not required.