science

John Day (carpenter)

John Day (carpenter) 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 Day (carpenter) rather than just read about it. In short: John Day (c. 1740 – 22 June 1774) was an English carpenter and wheelwright. He is the first recorded death in an accident with a submarine.

Key takeaways

John Day (carpenter) 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 Day (carpenter) to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of John Day (carpenter) from memory before moving on to harder problems.

Reference excerpt

John Day (c. 1740 – 22 June 1774) was an English carpenter and wheelwright. He is the first recorded death in an accident with a submarine. With the financial support of Christopher Blake, an English gambler, Day built a wooden "diving chamber" without an engine. He attached his invention to the deck of a 50-ton sloop named the Maria, which Blake had purchased for £340 (equivalent to £44,300 in 2025). The sloop's hold contained 10 tons of ballast, and two 10-ton weights were attached beneath the keel which could be released from inside the diving chamber. An additional 20 tons of ballast would be loaded on the Maria after Day had been locked inside the diving chamber. Day claimed he had previously spent 6 hours underwater in East Anglia in a different vessel. He bet with Blake that he and his boat could descend to a depth of 130 feet (40 m) and stay underwater for 12 hours. Blake lost his initial bets on the venture with other gamblers due to delays in the construction of the diving chamber that prevented Day from making the dive within an initially specified 3-month period. On 22 June 1774, the Maria was towed to a location north of Drake's Island (St. Nicholas' Island) in Plymouth Sound, off Plymouth, England. Day took a candle, water and biscuits on board. The boat was equipped with a hammock for the passenger. After the boat was locked, the weights were loaded and the boat sank forever into the depths. Day had the calculation of the trim completely wrong. It has been speculated that Day may have died from asphyxiation, hypothermia or catastrophic structural failure of the Maria and/or the diving chamber due to water pressure. Nikolai Detlef Falck mounted a rescue attempt a month after Day's descent, believing that Day might be alive in a form of suspended animation, but without success. In 1775, Falck published a pamphlet, A philosophical dissertation on the diving vessel projected by Mr Day, and sunk in Plymouth Sound, about Day's experiment. Day's death was the first recorded fatal accident involving a submarine.

Illustrations

Worked examples

Example 1 — a first encounter with John Day (carpenter)

Start with the simplest possible case. Write down what John Day (carpenter) 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 Day (carpenter) 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 Day (carpenter) 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 Day (carpenter)

In research: John Day (carpenter) 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 Day (carpenter) 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 Day (carpenter) is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1774 deaths, 18th-century British inventors, Accidental deaths in England, so understanding it makes those chapters shorter.
In everyday life: Look for John Day (carpenter) 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 Day (carpenter) in 20 minutes

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

Frequently asked questions

What is John Day (carpenter) in simple terms?

John Day (c. 1740 – 22 June 1774) was an English carpenter and wheelwright. He is the first recorded death in an accident with a submarine.

Why does John Day (carpenter) 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 Day (carpenter)?

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 Day (carpenter).