Convert Wedgwood to Reaumur like an 18th-century scientist
(1 °W - 1,077) ÷ 4.5 = -239.111 °Re
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Imagine trying to fire porcelain without modern thermometers. That's exactly what Josiah Wedgwood faced when developing his eponymous temperature scale in 1782. While you'll never need this conversion for baking cookies, understanding Wedgwood to Reaumur reveals fascinating insights into scientific history. These two scales represent different approaches to quantifying heat during the Enlightenment era, one rooted in ceramics and the other in wine-making. Let's dust off these antique measurements and see how they compare.
Unit definitions
What is a Wedgwood (°W)?
Description: An empirical temperature scale based on clay shrinkage
Symbol: °W
Common uses: Measuring kiln temperatures for pottery and porcelain
Definition: 1°W = 130°F above red heat (approximately 1077°F offset)
What is a Reaumur (°Re)?
Description: Alcohol expansion-based thermodynamic scale
Symbol: °Re
Common uses: Food production, particularly cheese aging and wine fermentation
Definition: Water freezes at 0°Re, boils at 80°Re (scale range: 0-80)
Conversion formula
The mathematical relationship established through comparative measurements:
°Re = (°W - 1077) / 4.5
°W = (°Re × 4.5) + 1077
Example calculations
- Converting 1300°W to Reaumur:
(1300 - 1077) = 223
223 ÷ 4.5 = 49.56°Re - Converting 60°Re to Wedgwood:
60 × 4.5 = 270
270 + 1077 = 1347°W
Conversion tables
Wedgwood to Reaumur
| °W | °Re |
|---|---|
| 1000 | -17.11 |
| 1100 | 5.11 |
| 1200 | 27.33 |
| 1300 | 49.56 |
| 1400 | 71.78 |
| 1500 | 94.00 |
Reaumur to Wedgwood
| °Re | °W |
|---|---|
| -20 | 987 |
| 0 | 1077 |
| 20 | 1167 |
| 40 | 1257 |
| 60 | 1347 |
| 80 | 1437 |
From pottery kilns to wine cellars: A heated history
The story begins with Josiah Wedgwood (yes, that Wedgwood of fine china fame) needing consistent temperatures for his ceramic glazes. His "pyrometric" scale used clay cylinder shrinkage - when a test piece shrank by 1/240th of its length, that defined 1°W. Practical for potters, but about as precise as a sundial in a thunderstorm.
Meanwhile in France, René Réaumur was calibrating his mercury-alcohol thermometers using wine spirits. His 1730 scale became the darling of dairies and vineyards. The connection between these systems? British ceramic engineers exporting wares to Europe needed conversion methods, leading to that odd 4.5 multiplier in our formula.
Fun fact: Early Wedgwood measurements required removing kiln bricks to insert clay samples, a dangerous process that occasionally ruined entire batches. Modern recreations show his scale roughly corresponded to 130°F increments starting from 1077°F, though consistency varied between kilns. The Reaumur scale meanwhile benefited from glassblowing advances, becoming the first truly portable temperature standard.
Interesting facts
- Wedgwood's daughter Susannah was Charles Darwin's mother, making the scale part of scientific royalty lineage
- Napoleon's army carried Reaumur thermometers for checking gunpowder storage conditions
- The 1077°F offset in Wedgwood's scale matches the ignition point of lead-based glazes
- Swiss Emmental cheese requires precise 20-25°Re during fermentation for proper hole formation
- Original Wedgwood pyrometers sold for £5 in 1785 - equivalent to $850 today
FAQ
While obsolete, historians and ceramic specialists occasionally reference Wedgwood scales when studying antique kiln records or reproducing historical pottery techniques.
The conversion is mathematically precise, but actual measurements from 18th-century instruments might have had ±5°W margin of error due to primitive tools.
Switzerland used Reaumur for chocolate production until the 1970s, and some Alpine cheesemakers still reference it in traditional recipes.
Like Celsius, 0°Re marks water's freezing point. However, its boiling point is 80°Re versus 100°C, making each degree 1.25 times larger.
The Victoria & Albert Museum displays original Wedgwood pyrometers used to test ceramic firing temperatures during the Industrial Revolution.