Used early thermoscopes; Santorio added a scale for medical use
Daniel Gabriel Fahrenheit
Instrument maker who produced accurate mercury thermometers
Anders Celsius
Swedish astronomer who proposed a centigrade scale
Plate 052
c. 1593–1714
Italy, the Dutch Republic, Sweden
No photograph is shown for this exhibition. The museum displays an image only where it can show the object honestly.
About this date
Galileo-style thermoscopes date to about 1593–1610 but had no standard scale. Daniel Fahrenheit built reliable mercury thermometers from 1714 and proposed a scale in 1724. Anders Celsius proposed his scale in 1742.
About credit
Many contributors. The instrument evolved from open thermoscopes to sealed, calibrated thermometers.
Chapter II
The world before
Life before the Thermometer
Heat was described by touch and by words. There was no agreed way to compare temperatures.
II
The human achievement
How it came about
Early thermoscopes used air and water and were affected by pressure. Fahrenheit sealed mercury in glass and set fixed points on a scale. Celsius’s scale, originally inverted, was later flipped to run from freezing to boiling at 0 and 100.
III
Understanding the invention
How it works
The Thermometer, explained in two steps.
01
Step 01 of 02
Expansion
Liquids occupy slightly more space as they warm.
Expansion
Fixed points
IV
The transformation
What changed for humanity
Medicine
Fever became measurable.
Science and industry
Experiments and processes could be controlled by temperature.
Measuring temperature turned “hot” and “cold” into numbers, essential for medicine, chemistry, weather and engineering.
V
Before and after
Life before and after The Thermometer
Before
Feeling a forehead.
After
Reading a number.
On larger screens, drag the divider (or use the arrow keys) to give more room to the world before or after.
VI
Its legacy
What came after
MHI 052
The Thermometer
Beyond the collection
Weather science
Thermometers are central to meteorology.
Beyond the collection
Digital sensors
Modern electronic thermometers use resistance or infrared.
VII
Human stories
The people and the moments
Celsius upside down
Celsius originally set 0 as the boiling point and 100 as freezing. The scale was reversed after his death in 1744.
Where accounts differ, this museum follows the documented record and says so.
