science

Principal meridian

Principal meridian 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 Principal meridian rather than just read about it. In short: A principal meridian is a meridian used for survey control in a large region. Canada The Dominion Land Survey of Western Canada took its origin at the First (or Principal) Meridian, located at 97°27′28.41″ west of Greenwich, just west of Winnipeg, Manitoba.

Key takeaways

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

Reference excerpt

A principal meridian is a meridian used for survey control in a large region.

Canada The Dominion Land Survey of Western Canada took its origin at the First (or Principal) Meridian, located at 97°27′28.41″ west of Greenwich, just west of Winnipeg, Manitoba. This line is exactly ten miles west of the Red River at the Canada–United States border. Six other meridians were designated at four-degree intervals westward, with the seventh located in British Columbia; the second and fourth meridians form the general eastern border and the western border of Saskatchewan.

United States

In the United States Public Land Survey System, a principal meridian is the principal north–south line used for survey control in a large region, and which divides townships between east and west. The meridian meets its corresponding baseline at the point of origin, or initial point, for the land survey. For example, the Mount Diablo Meridian, used for surveys in California and Nevada, runs north–south through the summit of Mount Diablo. Often, meridians are marked with roads, such as the Meridian Avenue in San Jose, California, Meridian Road in Vacaville, California, both on the Mount Diablo Meridian, Meridian Road in Wichita, Kansas on the Sixth Principal Meridian, and Meridian Avenue in several western Washington counties generally following the Willamette Meridian. Baseline Road or Base Line Street extends for about 40 miles (64 km) from Highland, California east of San Bernardino to La Verne, California where it meets Foothill Boulevard.

See also Cardo Baseline (surveying) List of principal and guide meridians and base lines of the United States

External links The Principal Meridian Project (US) History of the Rectangular Survey System Note: this is a large file, approximately 46MB. Searchable PDF prepared by the author, C. A. White. Resources page of the U.S. Department of the Interior, Bureau of Land Management

Worked examples

Example 1 — a first encounter with Principal meridian

Start with the simplest possible case. Write down what Principal meridian 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 Principal meridian 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 Principal meridian 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 Principal meridian

In research: Principal meridian 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 Principal meridian 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: Principal meridian is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cartography stubs, Geography terminology stubs, Meridians (geography), so understanding it makes those chapters shorter.
In everyday life: Look for Principal meridian 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 Principal meridian in 20 minutes

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

Frequently asked questions

What is Principal meridian in simple terms?

A principal meridian is a meridian used for survey control in a large region. Canada The Dominion Land Survey of Western Canada took its origin at the First (or Principal) Meridian, located at 97°27′28.41″ west of Greenwich, just west of Winnipeg, Manitoba.

Why does Principal meridian 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 Principal meridian?

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 Principal meridian.