How Did Scientists in the 13th Century Determine Temperature Changes?

History of Temperature

• Temperature affects physical, chemical and biological life. A complex understanding of temperature was slow to develop in history. The first recorded account of temperature measurement dates back to 167 AD. It wasn't until the late 16th century that a thermoscope was designed to astutely measure temperature. Galileo produced the first thermometer in the early 17th century.

Measurement Scale in 13th century

• Galen (AD 130-200) followed Aristotle's study of assigning hot and cold a relative number. Galen essentially developed the first temperature scale. He proposed a neutral temperature standard by melting ice in boiling water. The scale consisted of four degrees of heat and four of cold below and above the neutral point. With this standard, a number of fixed points could define temperature, however the scale still lacked intermediate levels. Temperature measurement was subjective, and man was forced to rely on senses.

Visual Indications

• When materials reach a certain temperature, they display identifiable characteristics. Steam and bubbles form from water and other liquids to signify a boiling point. The color of heated materials also indicates temperature change. Water slowly turns to ice at colder temperatures and gives off water vapor when introduced to heat. Testing materials with fire challenged a number of the material's properties.

Touch

• People can instinctually sense temperature change. The realization that cold and hot are binary has preceded the concept of temperature measurement in history. The skin is an effective catalyst of sensing temperature change. Touch can identify temperature with or without direct contact. As many materials emanate heat or cold when exposed to temperature extremes, the skin can sense within proximity.

Heat

• Greater knowledge was gained as early man attempted to work with fire -- cooking, making fire for warmth, hardening pottery, boiling water even forging metals like iron, tin and bronze. Producing and tools requires a level of technological understanding over fire's effect on temperature. With such means of controlling temperature, man could test other materials with fire.