science

John Francillon

John Francillon 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 John Francillon rather than just read about it. In short: John Francillon (1744–1816) was a jeweler and lapidary, an English naturalist and an entomologist of Huguenot descent. Francillon was a London jeweller who was also a dealer in natural history specimens and paintings.

Key takeaways

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

Reference excerpt

John Francillon (1744–1816) was a jeweler and lapidary, an English naturalist and an entomologist of Huguenot descent. Francillon was a London jeweller who was also a dealer in natural history specimens and paintings. He was the agent for John Abbot selling his American bird and natural history illustrations. He maintained a large insect collection. Some of his butterflies appear in the Icones of William Jones. He was a Fellow of the Linnean Society.

The Francillon Memo In September 1812 Francillon was allowed to trace around an unset 45.5-carat (9.10 g) blue cushion-shaped diamond in the possession of the diamond merchant Daniel Eliason. Francillon drew the diamond in plan and elevation, coloring the plan drawing to match the deep blue color of the stone. Below the drawings he wrote notes to explain that he had been given permission to draw the gem by its owner, Eliason, and that it was " ... a very curious superfine deep blue Diamond." "There is other evidence which places a 44-carat blue diamond in England at least as early as 1812." George Frederick Kunz, a distinguished American gemologist, told of finding two detailed sketches of the Hope Diamond made by a Soho lapidary in 1812. As he explained in an article in The Saturday Evening Post, Kunz discovered the sketches in an old book by Pouget that he found one day while browsing in Quartich's bookshop in London. It is now known that this rare blue diamond was once part of the missing Royal and Imperial crown jewels of France. It was commonly known as the French Blue and had been set into Louis XV's jeweled insignia for the Order of the Golden Fleece. The French Blue had been stolen on 11 September 1792 along with most of the French Crown Jewels and was never recovered. The Francillon Memo is the first record of the diamond which would come to be known as the Hope Diamond. Francillon's drawing is dated two days after the statute of limitations for recovering French stolen property in the Napoleonic Code had expired. Who sold the stone to Eliason is unclear, as is how long it was in his possession before he allowed Francillon to view and draw it. Also a mystery is who authorized the cutting of the French Blue to form the Hope Diamond. The Francillon Memorandum says: "The above drawing is the exact size and shape of a very curious superfine deep blue Diamond. Brilliant cut, and equal to a fine deep blue Sapphire. It is beauty full and all perfection without specks or flaws, and the color even and perfect all over the Diamond. I traced it round the diamond with a pencil by leave of Mr. Daniel Eliason and it is as finely cut as I have ever seen in a Diamond. The color of the Drawing is as near the color of the Diamond as possible. Dated: 19th September, 1812. John Francillon, No. 29 Norfolk Street, Strand, London." The Francillon Memorandum remains in the Pouget book today, in the George Frederick Kunz Collection of the United States Geological Survey Library in Reston, Virginia. The Pouget book was donated to the USGS as part of Mr. Kunzs' private library after his death in 1933.

Media A small image of Francillon's memorandum can be seen at PBS Treasures of the World page which provides details of the Hope Diamond's provenance. The Francillon Memo is pictured in highlights for a December 2010 special on the "Secrets of the Hope Diamond" for the National Geographic Channel.

Obituary "June 23 John Francillon esq. of Norfolk Street Strand a gentleman much esteemed for his amiable manners and conduct throughout life, and possessed of a superb cabinet of foreign insects the assiduous labour and cost of many years."

References

Further reading Ian Balfour, Famous Diamonds, London: William Collins & Sons, Publishers, 1987. hardcover, ISBN 0-00-412246-1. Marian Fowler, Hope: Adventures of a Diamond, Ballantine (March, 2002), hardcover, ISBN 0-345-44486-8. Kunz, George F., Ray M. B. (1928) "The gem collector in Europe." Saturday Evening Post, 21 January 1928, pp. 33–34, 36, 38. Richard Kurin, Hope Diamond: The Legendary History of a Cursed Gem, New York: HarperCollins Publishers & Smithsonian Press, 2006. hardcover, ISBN 0-06-087351-5. Patch, Susanne Steinem. Blue mystery: the story of the Hope diamond. [Washington, D.C.]; New York: Abrams, 1999. 92 pages: ill. (some col.); 18 cm. National Museum of Natural History, Smithsonian Institution in association with Harry N. Abrams, Inc., publishers. Includes bibliographical references. ISBN 0-8109-2797-7. Pouget, Jean Henri Prosper. 1762. Traité des pierres précieuses et de la maniere de les employer en parure. Paris: Chez l'auteur [etc.], 1762. 88 pages, 79 leaves of plates: color illustrations; 25 cm. In the USGS Library, Reston, Virginia; the publication is part of the George Frederick Kunz Collection. Library copy 2 includes Francillon Memorandum and diamond illustration dated 19 September 1812. Copy 1 lacks illustration. Notes: Engraved illustrated t.-p. after original design by J.B. Piauger. Plates engraved by Mlle, Raimbau. "Catalogue des auteurs," p. 35-39.

External links Media related to John Francillon at Wikimedia Commons

Worked examples

Example 1 — a first encounter with John Francillon

Start with the simplest possible case. Write down what John Francillon 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 John Francillon 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 John Francillon 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 John Francillon

In research: John Francillon 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 John Francillon 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: John Francillon is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1744 births, 1816 deaths, 19th-century British naturalists, so understanding it makes those chapters shorter.
In everyday life: Look for John Francillon 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 John Francillon in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what John Francillon 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 John Francillon out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is John Francillon in simple terms?

Why does John Francillon 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 John Francillon?

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 John Francillon.