physics

John Canton

John Canton is a physics 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 Canton rather than just read about it. In short: John Canton (31 July 1718 – 22 March 1772) was a British physicist. He was born in Middle Street Stroud, Gloucestershire, to a weaver, John Canton (b. 1687) and Esther (née Davis).

Key takeaways

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

Reference excerpt

John Canton (31 July 1718 – 22 March 1772) was a British physicist. He was born in Middle Street Stroud, Gloucestershire, to a weaver, John Canton (b. 1687) and Esther (née Davis). As a schoolboy, he became the first person to determine the latitude of Stroud, while making a sundial. The sundial caught the attention of many, including Dr Henry Miles, a Stroud-born Fellow of the Royal Society. Miles encouraged Canton to leave Gloucestershire to become a trainee teacher for Samuel Watkins, the headmaster of a Nonconformist school in Spital Square, London, with whom he ultimately entered into partnership.

In 1750 he read a paper before the Royal Society on a method of making artificial magnets, and was subsequently elected a Fellow of the society (FRS). In 1751 he was a recipient of the Copley Medal "On account of his communicating to the Society, and exhibiting before them, his curious method of making Artificial Magnets without the use of Natural ones." He was the first in England to verify Benjamin Franklin's hypothesis of the identity of lightning and electricity, and he made several important electrical discoveries. In 1762 and 1764 he published experiments in refutation of the decision of the Florentine Academy, at that time generally accepted, that water is incompressible. He put a hollow glass sphere with a thin capillary tube on it, and filled the sphere with water. He put the entire thing under an air pump, and changed the pressure between 2 atm and a near vacuum. He observed that the water rose up the capillary when in a near vacuum, and vice versa. He thus concluded that an increase of 1 atm would compress water by 1/10870 in volume. This agrees with modern value for the bulk modulus of water to within 3%. He also studied the compressibility of spirit of wine, olive oil, mercury and seawater, etc., and found that the compressibility increased with a decrease in density. In 1768 he described the preparation, by calcining oyster-shell with sulphur, of the phosphorescent material known as Canton's phosphorus. His investigations were carried on while he worked as a school teacher. He died in London aged 53 of dropsy. He was the recipient of letters that formed the foundation for modern day Bayes' Theorem from Thomas Bayes, which were then published by the Royal Society. John Canton did not receive those letter directly from Bayes, but through an intermediary after the death of Thomas Bayes. Richard Price initially established the communication between Thomas Bayes and John Canton. Canton is now mainly remembered for his work in electrostatics, particularly the invention of the pith ball electroscope, and his studies in atmospheric electricity. He is honoured with a blue plaque at the site of his old school in his hometown of Stroud.

References

External links Media related to John Canton at Wikimedia Commons Works by John Canton at Project Gutenberg Works by or about John Canton at the Internet Archive

Illustrations

Worked examples

Example 1 — a first encounter with John Canton

Start with the simplest possible case. Write down what John Canton claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In physics, 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 Canton 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 Canton 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 Canton

In research: John Canton appears in physics 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 Canton 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 Canton is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1718 births, 1772 deaths, 18th-century English people, so understanding it makes those chapters shorter.
In everyday life: Look for John Canton 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 Canton in 20 minutes

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

Frequently asked questions

What is John Canton in simple terms?

John Canton (31 July 1718 – 22 March 1772) was a British physicist. He was born in Middle Street Stroud, Gloucestershire, to a weaver, John Canton (b. 1687) and Esther (née Davis).

Why does John Canton matter?

Because it connects several physics 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 Canton?

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 Canton.