Thermometer Developed Slowly
In Early Stages
Galileo is given credit for inventing the first thermometer, in 1592. It was strictly a laboratory instrument and inconvenient to use. Furthermore, no one seemed to find it a very necessary piece of equipment.
Various adaptations were made sporadically for the next 150 years. In none of them were accurate readings possible.
Among the non-standard features were what should be used as the fixed ends of heat on the instrument, and what scale should be used for changes in temperature. For a while, the fixed points were the temperatures of freezing water and melting butter.
In the early 1700s, scientific interest in the idea of a thermometer became more serious, and the present-day fixed points of freezing and boiling water were adopted. The scale in between was not standardized, however, and gaps between the ends were filled in as one wished.
Fahrenheit developed his model and scale in 1717, using mercury as the movable liquid. A scientist named Reaumur developed a model that used spirits of wine to expand and contract. The Centigrade, or Celsius, scale was developed in 1742.
An individualist named deLisle worked in the opposite direction. His thermometer used 0 as the point at which “Water boyles vehemently” and 160 as “Just Freezing.”
Most of the problems concerning thermometer making were settled by the 19th century, and the instrument came into common use for a variety of purposes.
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