science

Traditional French units of measurement

Traditional French units of measurement is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Traditional French units of measurement rather than just read about it. In short: The traditional French units of measurement prior to metrication were established under Charlemagne during the Carolingian Renaissance. Based on contemporary Byzantine and ancient Roman measures, the system established some consistency across his empire but, after his death, the empire fragmented and subsequent rulers and various localities introduced their own variants.

Key takeaways

Traditional French units of measurement belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Traditional French units of measurement to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Traditional French units of measurement from memory before moving on to harder problems.

Reference excerpt

The traditional French units of measurement prior to metrication were established under Charlemagne during the Carolingian Renaissance. Based on contemporary Byzantine and ancient Roman measures, the system established some consistency across his empire but, after his death, the empire fragmented and subsequent rulers and various localities introduced their own variants. Some of Charlemagne's units, such as the king's foot (French: pied du Roi) remained virtually unchanged for about a thousand years, while others important to commerce—such as the French ell (aune) used for cloth and the French pound (livre) used for amounts—varied dramatically from locality to locality. By the 18th century, the number of units of measure had grown to the extent that it was almost impossible to keep track of them and one of the major legacies of the French Revolution was the dramatic rationalization of measures by the new metric system. The change was extremely unpopular, however, and a metricized version of the traditional units—the mesures usuelles—had to be brought back into use for several decades.

History

Although in the pre-revolutionary era (before 1795) France used a system and units of measure that had many of the characteristics of contemporary English units (or the later Imperial System of units), France still lacked a unified, countrywide system of measurement. Whereas in England Magna Carta had decreed that "there shall be one unit of measure throughout the realm", Charlemagne and successive kings had tried but failed to impose a unified system of measurement in France. The names and relationships of many units of measure were adopted from Roman units of measure, and many more were added – it has been estimated that there were seven or eight hundred different names for the various units of measure. Moreover, the quantity associated with each unit of measure differed from town to town and even from trade to trade. Some of the differences were large: for example the lieue (league) could vary from 3.268 km in Beauce to 5.849 km in Provence. It has been estimated that on the eve of the Revolution a quarter of a million different units of measure were in use in France. Although certain standards, such as the pied du Roi (the King's foot) had a degree of pre-eminence and were used by savants, many traders chose to use their own measuring devices, giving scope for fraud and hindering commerce and industry.

Tables of units of measure

These definitions use the Paris definitions for the coutume of Paris, and definitions for other Ancien régime civil jurisdictions varied, at times quite significantly.

Length The medieval royal units of length were based on the toise, and in particular the toise de l'Écritoire, the distance between the fingertips of the outstretched arms of a man, which was introduced in 790 by Charlemagne. The toise had 6 pieds (feet) each of 326.6 mm (12.86 in). In 1668 the reference standard was found to have been deformed, and it was replaced by the toise du Châtelet which, to accommodate the deformation of the earlier standard, was around 11 mm (0.56%) shorter. In 1747 this toise was replaced by a new toise of near-identical length – the Toise du Pérou, custody of which was given to l'Académie des Sciences au Louvre. Although the pouce (inch), pied (foot) and toise (fathom) were fairly consistent throughout most of pre-revolutionary France, some areas had local variants of the toise. Other units of measure such as the aune (ell), the perche (perch or rood), the arpent and the lieue (league) had a number of variations, particularly the aune (which was used to measure cloth). The loi du 19 frimaire an VIII (Law of 10 December 1799) states that one decimal metre is exactly 443.296 French lines, or 3 pieds 11.296 lignes de la "Toise du Pérou". Thus the French royal foot is exactly ⁠4500/13 853⁠ metres (about 0.3248 m (12.79 in)). In Quebec, the surveys in French units were converted using the relationship 1 pied (of the French variety, the same word being used for English feet as well) = 12.789 English inches. This makes the Quebec pied very slightly smaller (about 4 parts in one million) than the pied used in France.

The French typographic point, the Didot point, was 1⁄72 of a French inch, i.e. two royal points. The French pica, called Cicéro, measured 12 Didot points or 12 × 0.376 = 4.512 mm (0.1776 in).

Area

Volume – liquid measures

Volume – dry measures

Weight

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Traditional French units of measurement

Start with the simplest possible case. Write down what Traditional French units of measurement claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Traditional French units of measurement before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Traditional French units of measurement ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Traditional French units of measurement

In research: Traditional French units of measurement appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Traditional French units of measurement in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Traditional French units of measurement is common in secondary-school and first-year university syllabi. It links to neighbouring topics Science and technology in France, Systems of units, Traditional French units of measurement, so understanding it makes those chapters shorter.
In everyday life: Look for Traditional French units of measurement outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Traditional French units of measurement in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Traditional French units of measurement means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Traditional French units of measurement out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Traditional French units of measurement in simple terms?

Why does Traditional French units of measurement matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Traditional French units of measurement?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Traditional French units of measurement.