science

Kunitomo Ikkansai

Kunitomo Ikkansai 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 Kunitomo Ikkansai rather than just read about it. In short: Kunitomo Ikkansai (国友一貫斎; November 21, 1778 – December 26, 1840), real name Kunitomo Tōbee Yoshimasa (国友藤兵衛能當), was a Japanese gunsmith and inventor of the late Edo period, who, after having spent several months in Edo, where he could get accustomed with Dutch wares, built Japan's first reflective telescope in 1831. It was of the Gregorian type and had a magnification of 60.

Key takeaways

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

Reference excerpt

Kunitomo Ikkansai (国友一貫斎; November 21, 1778 – December 26, 1840), real name Kunitomo Tōbee Yoshimasa (国友藤兵衛能當), was a Japanese gunsmith and inventor of the late Edo period, who, after having spent several months in Edo, where he could get accustomed with Dutch wares, built Japan's first reflective telescope in 1831. It was of the Gregorian type and had a magnification of 60. He used it to make very detailed studies of sun spots and lunar topography. Four of his telescopes remain to this day. In the early 19th century, Kunitomo became an acquaintance of the Shinto theologian and nativist Hirata Atsutane, and was in regular contact with him. Around this time, Kunitomo was involved in the development of firearm manufacturing methods. Circa 1820, he designed a pneumatic rifle based on his studies of European air rifle technology conducted through the Dutch trading post at Dejima.

Other uses of the name 6100 Kunitomoikkansai, a main belt asteroid discovered in 1991, is named after Kunitomo Ikkansai.

References Plane drawings created by Ikkansai, connecting parts for a reflecting telescope.　Nagahama City Citizen Collaboration Department, Historical Heritage Section, research into the Kunitomo Ikkansai family records. Subsidized by the Agency for Cultural Affairs. Documents of the Kunitomo Ikkansai family Reflecting telescope (owned by Nagahama Castle History Museum, Nagahama City)

Illustrations

Worked examples

Example 1 — a first encounter with Kunitomo Ikkansai

Start with the simplest possible case. Write down what Kunitomo Ikkansai 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 Kunitomo Ikkansai 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 Kunitomo Ikkansai 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 Kunitomo Ikkansai

In research: Kunitomo Ikkansai 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 Kunitomo Ikkansai 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: Kunitomo Ikkansai is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1778 births, 1840 deaths, Firearm designers, so understanding it makes those chapters shorter.
In everyday life: Look for Kunitomo Ikkansai 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 Kunitomo Ikkansai in 20 minutes

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

Frequently asked questions

What is Kunitomo Ikkansai in simple terms?

Why does Kunitomo Ikkansai 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 Kunitomo Ikkansai?

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 Kunitomo Ikkansai.